Really good work Rick and Bob.
I made my own PCB's in december but have drowned in work.
With +/-60V and 4 pairs 2SJ55/2SK175 I got really low distortion, about 0.0047% at full output. A bit Hfe matchning and J-fets had a diff of 1.8mA, around 7.5mA IIRC.
My plan is to test it with +/- 75V and boosted rail for drivers.
BR
Figge
I made my own PCB's in december but have drowned in work.
With +/-60V and 4 pairs 2SJ55/2SK175 I got really low distortion, about 0.0047% at full output. A bit Hfe matchning and J-fets had a diff of 1.8mA, around 7.5mA IIRC.
My plan is to test it with +/- 75V and boosted rail for drivers.
BR
Figge
Hi Chris,
In fact the DH-220C design was thought out to be generic enough that it can be used without a Hafler chassis, since it consists of a front end/driver (AFE) board and separate output stage(OPS) boards. The two types of OPS boards are designed to fit, four or six TO-3P, TO-247 or TO-264 plastic packaged devices soldered directly to the board or as in the Hafler case, short wires are used to the TO-3 sockets. See Post #1682 for pictures of the boards.
I ran the AFE the other day at +/-90V, it survived okay, the drivers were pretty hot to touch, with the small clip on heatsinks. So a more efficient heatsink for them is warranted, but that can be as simple as a larger piece of thin Aluminium plate, running between the devices, for more surface area.
Rick
In fact the DH-220C design was thought out to be generic enough that it can be used without a Hafler chassis, since it consists of a front end/driver (AFE) board and separate output stage(OPS) boards. The two types of OPS boards are designed to fit, four or six TO-3P, TO-247 or TO-264 plastic packaged devices soldered directly to the board or as in the Hafler case, short wires are used to the TO-3 sockets. See Post #1682 for pictures of the boards.
I ran the AFE the other day at +/-90V, it survived okay, the drivers were pretty hot to touch, with the small clip on heatsinks. So a more efficient heatsink for them is warranted, but that can be as simple as a larger piece of thin Aluminium plate, running between the devices, for more surface area.
Rick
Thanks, Figge. Keep us posted on your results, especially in regard to the boosted rails. Boosted rails can make a big difference, especially on peak power, since, if done properly, the boosted rails don't sag nearly as quickly as the mail rails, since they will have their own rectifiers and (smaller) reservoir capacitors. In fact, even without additional windings, quasi-boosted rails, where you have just separate rectifiers and reservoir capacitors for the AFE, running off the main windings, can help a lot due to less sag and longer time to sag. Those who have gone to toroids can hand-wind the extra windings onto the power transformer to create the boosted rails. Most toroid power transformers produce between 0.6 and 1.0 volt per turn, so it does not take that many turns for each of the boost windings. Moreover, those turns can be implemented with small AWG wire.
It is much less helpful to create boosted rails by adding a floating low-voltage DC supply on top of the mail rails, as it will then retain the ripple and sag of the main rails.
Cheers,
Bob
Hi Chris,
Yes it would be a DIY project requiring the use of old or new parts. Of course using the old Hafler’s is an advantage since everything is contained.
J201 & K1530 are not lateral types, thus need thermal compensation. Not impossible but a deviation from the design. Would need to mount one of the bias spreader bjts on the heat sink or on top of one of the Fets. Need to check if they are the same pin out, I think that they are not, drain is case, would need remote mounting. I could one day design another OPS pcb for that package. Not too much to them.
Yes it would be a DIY project requiring the use of old or new parts. Of course using the old Hafler’s is an advantage since everything is contained.
J201 & K1530 are not lateral types, thus need thermal compensation. Not impossible but a deviation from the design. Would need to mount one of the bias spreader bjts on the heat sink or on top of one of the Fets. Need to check if they are the same pin out, I think that they are not, drain is case, would need remote mounting. I could one day design another OPS pcb for that package. Not too much to them.
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Not too many of them around in these parts. I put an ad on Canuck audio mart and got one bite, I made a deal that I would upgrade one in exchange to keep the other, so I was lucky. The guy was from North Bay, he was coming down to TO, so we met up at #400 parking lot. Shipping these heavy amps gets expensive, same as there value. Some have offered me DH-500’s, imo they are too expensive to ship. Maybe I’ll advertise locally for one of them now that I think of it.
There are the Dh-220, p225, p230 options of the same design, the p models are the rack mount chassis.
There are the Dh-220, p225, p230 options of the same design, the p models are the rack mount chassis.
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Thanks to all that replied, sorry for the delay on my part, for some reason I am not seeing the "replied to" emails and just got around to checking manually.
I agree something is wrong with my amp due to the hum (from both speakers with no input connected). I have it splayed out for inspection now and the input wire on the right board broke off, as if it were connected by only a strand or two...
...initially I had thought this was a factory amp because the boards look factory made, now I realize this kit came with assembled amp modules that you just wire together, right? So this could be a kit after all... hence the bad soldering on the input wire and probably elsewhere.
My thought was, the amp is old, I should re-cap it, at least electrolytics. As far as I can see the power supply is basically the bridge rectifier, two 10,000uf filter caps and c21/22 which are .1uf film caps.
I figure I should rip the wiring and start anew, in the process might as well replace the rectifier and would like to replace the cans for good measure, the films IDK if I need to bother? at least initially...
I would be interested in suggestions for what type of bridge to buy and recommendations on filter caps models and value, should I stick to 10K uf or bump it up a bit? Keeping in mind that this amp will ultimate end up powering a sub.
I was planning on shopping digikey, have selected replacements for C8,12,14 already (nichicon muse) but haven't decided on the cans. I figure while ordering from Digikey I should get new wire, maybe order up film caps for the next step in the upgrade after I get her running silent with new power supply and wiring. Suggestions on best wire to use would be appreciated, it's soo hard to tell what is what when you can't hold it in your hand.
At ay rate, thanks again for all your input, further input on the above would be appreciated... I am going to try to get this digikey order together this weekend....
I agree something is wrong with my amp due to the hum (from both speakers with no input connected). I have it splayed out for inspection now and the input wire on the right board broke off, as if it were connected by only a strand or two...
...initially I had thought this was a factory amp because the boards look factory made, now I realize this kit came with assembled amp modules that you just wire together, right? So this could be a kit after all... hence the bad soldering on the input wire and probably elsewhere.
My thought was, the amp is old, I should re-cap it, at least electrolytics. As far as I can see the power supply is basically the bridge rectifier, two 10,000uf filter caps and c21/22 which are .1uf film caps.
I figure I should rip the wiring and start anew, in the process might as well replace the rectifier and would like to replace the cans for good measure, the films IDK if I need to bother? at least initially...
I would be interested in suggestions for what type of bridge to buy and recommendations on filter caps models and value, should I stick to 10K uf or bump it up a bit? Keeping in mind that this amp will ultimate end up powering a sub.
I was planning on shopping digikey, have selected replacements for C8,12,14 already (nichicon muse) but haven't decided on the cans. I figure while ordering from Digikey I should get new wire, maybe order up film caps for the next step in the upgrade after I get her running silent with new power supply and wiring. Suggestions on best wire to use would be appreciated, it's soo hard to tell what is what when you can't hold it in your hand.
At ay rate, thanks again for all your input, further input on the above would be appreciated... I am going to try to get this digikey order together this weekend....
Good luck Chris in finding one, if I see one I'll let you know.
I was surprised to see that Dig-key is selling wire by the foot, good for them and the small guy constructors. Use #18 AWG for the high current/AC paths, #20-22 is fine for the other stuff. The wire they list looks to be good quality, just do not use solid wire. I am going to have to get some (ETFE) and check it out.
Not sure why the wires need to be changed, I do not think it will make any difference. Cosmetic to me. Unless the wires are too short.
I do not think you need to change the bridge diode, it is a 25A part, sealed in epoxy. You could bump the ecap value up to 15mF, maybe 22mF, it is just harder on that poor A/C switch.
I was surprised to see that Dig-key is selling wire by the foot, good for them and the small guy constructors. Use #18 AWG for the high current/AC paths, #20-22 is fine for the other stuff. The wire they list looks to be good quality, just do not use solid wire. I am going to have to get some (ETFE) and check it out.
Not sure why the wires need to be changed, I do not think it will make any difference. Cosmetic to me. Unless the wires are too short.
I do not think you need to change the bridge diode, it is a 25A part, sealed in epoxy. You could bump the ecap value up to 15mF, maybe 22mF, it is just harder on that poor A/C switch.
[a cream puff] DH200 on eBay for 239.00
I must be confused... they are 'out there'
Used DH200 for Sale | HifiShark.com
1/2 dozen are shown, listed for sale...
This is a very clean amp ...surprisingly so...
Vintage Hafler DH 200 Power Amp | eBay
Even a scratch and dent one for 100.00,
worthy of reworking... budget saved would
easily offset cost of parts, to ship or rebuild.
*hope that posting any link, is not a breach in DIY Audio policy,
I am not the seller. Not a 'self promotion' effort.
Only want to direct, per the request.
...delete if so...
I must be confused... they are 'out there'
Used DH200 for Sale | HifiShark.com
1/2 dozen are shown, listed for sale...
This is a very clean amp ...surprisingly so...
Vintage Hafler DH 200 Power Amp | eBay
Even a scratch and dent one for 100.00,
worthy of reworking... budget saved would
easily offset cost of parts, to ship or rebuild.
*hope that posting any link, is not a breach in DIY Audio policy,
I am not the seller. Not a 'self promotion' effort.
Only want to direct, per the request.
...delete if so...
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My rational for rewiring... (not meant as a challenge)
I am quite allergic, much of the amps that I see have been used in bars, businesses or in a smokers home (not a knock to those) there is a smelly, oily crud, (cooking oils?) funk on all the internals, virtually on every surface. *I wash the entire chassis, inside and out, with citrus based cleaner and/or alcohol... so 'my amps' do not emit a funky odor in the room as they heat up and during use. **I believe, 2nd and 3rd hand off gassing to be (not good) toxic, another discussion entirely...
I also completely 'rewire', use the same exact wire and parts to eliminate, intra-chassis variables, that may additively impact build variability, and to ensure greater continuity in the wire dressing of all my individual work and to make every single solder connection myself (eliminating another variable) I know what I am working with, no second guessing...
And some people (kit builders) can use old or funky solder, that 'may be' another variable and/or be [hidden] source to cold solder joints, tell-tale veiling and noise.
Over the years, I have seen too many (kit built) amps, where people have done poor wire stripping [often hidden] cutting the conductor bundles.
~ for me ~ not an OCD or simple aesthetic element, I do it for continuity across the board, often is the case, a tidy amp ...is generally a great sounding amp...
Often [too many] kit builders, cut their teeth, learning to solder (I am sorry, make mistakes) on these products, it is easy to inherit another persons mistakes... that may reflect on my efforts... Every piece I build, is done with the prospect of possible resale. My name and 'reputation' is on it, I do not see my gear come back 'broken'.
**Often, when I turn over, and sell my *proof of concept* project amps... I KNOW EXACTLY what I am handing over to that person... These amps ..are.. for practical purposes, "new amps" in nearly every sense of the expression.
I am quite allergic, much of the amps that I see have been used in bars, businesses or in a smokers home (not a knock to those) there is a smelly, oily crud, (cooking oils?) funk on all the internals, virtually on every surface. *I wash the entire chassis, inside and out, with citrus based cleaner and/or alcohol... so 'my amps' do not emit a funky odor in the room as they heat up and during use. **I believe, 2nd and 3rd hand off gassing to be (not good) toxic, another discussion entirely...
I also completely 'rewire', use the same exact wire and parts to eliminate, intra-chassis variables, that may additively impact build variability, and to ensure greater continuity in the wire dressing of all my individual work and to make every single solder connection myself (eliminating another variable) I know what I am working with, no second guessing...
And some people (kit builders) can use old or funky solder, that 'may be' another variable and/or be [hidden] source to cold solder joints, tell-tale veiling and noise.
Over the years, I have seen too many (kit built) amps, where people have done poor wire stripping [often hidden] cutting the conductor bundles.
~ for me ~ not an OCD or simple aesthetic element, I do it for continuity across the board, often is the case, a tidy amp ...is generally a great sounding amp...
Often [too many] kit builders, cut their teeth, learning to solder (I am sorry, make mistakes) on these products, it is easy to inherit another persons mistakes... that may reflect on my efforts... Every piece I build, is done with the prospect of possible resale. My name and 'reputation' is on it, I do not see my gear come back 'broken'.
**Often, when I turn over, and sell my *proof of concept* project amps... I KNOW EXACTLY what I am handing over to that person... These amps ..are.. for practical purposes, "new amps" in nearly every sense of the expression.
YMMV 
Sure you can use new wire, if it is new vinyl, it will probably out gas for years. Yum, a fresh new supply of it, just what the Dr ordered. I would never buy a new vehicle, the out gassing of the plastics makes me sick. I know, I held my head out the window of the Uncles new Olds Vista Cruiser as a kid, from Toronto to Thunder Bay, just awful stuff. It takes a number of years for that to clear. I hope you are using PTFE (teflon) wire in your mods and not that cheap vinyl stuff. To each there own, as they say, I am not sold.
Sure you can use new wire, if it is new vinyl, it will probably out gas for years. Yum, a fresh new supply of it, just what the Dr ordered. I would never buy a new vehicle, the out gassing of the plastics makes me sick. I know, I held my head out the window of the Uncles new Olds Vista Cruiser as a kid, from Toronto to Thunder Bay, just awful stuff. It takes a number of years for that to clear. I hope you are using PTFE (teflon) wire in your mods and not that cheap vinyl stuff. To each there own, as they say, I am not sold.[unknowingly] inheriting 'others mistakes'.
Rick, this is not a criticism, I cringed when I saw it...
[I HAVE IMMENSE RESPECT FOR YOUR WORK]
I reworked this on my very first DH200 amp in 1980,
it popped in my view, as I first saw it, when building.
There should be no shared wire between left and right
channel fuse blocks... very common, even on
factory wired units. Except most "p-series" product,
as this became understood and addressed.
There ~ should be ~ 2 separate wires from capacitor
to each fuse block, so that there is not shared power
for left and right channels. **Again, not a criticism.
I rewire most things that cross my work bench
*this being one of several things I address...
image 1) your original image *post #1682
image 2) a close crop (I made) to better illustrate.
- - - -
image 3) a good friend sent me his 220, with a loud buzz
that we figured was bad caps... he never opened the
case. I was going to rebuild, recap, (yes) rewire,
and 'touch' every single solder point...
image 4) this amp, was among the most pristine
externally, a real cream puff, *with mistakes*
only 2 shared wires, would never know...
~ I clearly have touched a nerve, will back away ~
Rick, this is not a criticism, I cringed when I saw it...
[I HAVE IMMENSE RESPECT FOR YOUR WORK]
I reworked this on my very first DH200 amp in 1980,
it popped in my view, as I first saw it, when building.
There should be no shared wire between left and right
channel fuse blocks... very common, even on
factory wired units. Except most "p-series" product,
as this became understood and addressed.
There ~ should be ~ 2 separate wires from capacitor
to each fuse block, so that there is not shared power
for left and right channels. **Again, not a criticism.
I rewire most things that cross my work bench
*this being one of several things I address...
image 1) your original image *post #1682
image 2) a close crop (I made) to better illustrate.
- - - -
image 3) a good friend sent me his 220, with a loud buzz
that we figured was bad caps... he never opened the
case. I was going to rebuild, recap, (yes) rewire,
and 'touch' every single solder point...
image 4) this amp, was among the most pristine
externally, a real cream puff, *with mistakes*
only 2 shared wires, would never know...
~ I clearly have touched a nerve, will back away ~
Attachments
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You did not touch a nerve, but making a blanket statement than they all should be re-wired needs to be qualified as to why, what to use, how. You did touch on some of the reasons which are fine, but I think evaluation can be done, some touch ups can be done without resorting to gutting it and a complete rebuild. It might not be necessary and if done incorrectly could make an operational unit non-operational. I see this a lot even with re-capping efforts.
On my unit, that you show, it was wired by the original owner. I did not even bother to evaluate or question it. I see what you mean however, it could be improved upon as you describe. Nothing wrong with finding faults in the manufactures methods and materials, suggesting improvement, i am all for that, since that is what we are doing by designing new boards.
As you are suggesting to others to re-wire them, some might just wire them up as they were done originally and not even question if they were done properly in the first place. Now that I look at the Hafler instructions, my unit is wired per the instructions, but I do agree with you that it can be optimized, as you suggest. How much difference it makes I am not too sure of but it certainly would not hurt to do it the way that you suggest. Everyone take note. If you have other suggestions for improvements, make an itemized list of them, so everyone is aware of them and they can decide if they want to implement. Nothing wrong with that.
I did not mention that I have been getting my teflon wire from a eBay seller "superiorbuy2014". It is PTFE FEP Wire High Temp. Stranded Cable UL1332. If I could get it locally in small quantities, 5m lengths, I would but I do not know of anyone selling it.
On my unit, that you show, it was wired by the original owner. I did not even bother to evaluate or question it. I see what you mean however, it could be improved upon as you describe. Nothing wrong with finding faults in the manufactures methods and materials, suggesting improvement, i am all for that, since that is what we are doing by designing new boards.
As you are suggesting to others to re-wire them, some might just wire them up as they were done originally and not even question if they were done properly in the first place. Now that I look at the Hafler instructions, my unit is wired per the instructions, but I do agree with you that it can be optimized, as you suggest. How much difference it makes I am not too sure of but it certainly would not hurt to do it the way that you suggest. Everyone take note. If you have other suggestions for improvements, make an itemized list of them, so everyone is aware of them and they can decide if they want to implement. Nothing wrong with that.
I did not mention that I have been getting my teflon wire from a eBay seller "superiorbuy2014". It is PTFE FEP Wire High Temp. Stranded Cable UL1332. If I could get it locally in small quantities, 5m lengths, I would but I do not know of anyone selling it.
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Really, #18 and #20 wire, seems kinda thin?
You are correct, looks like a 25A bridge, no reason to suspect it is faulty. However, I read if you bump up the filter caps to 18,000uf you should bump up the rectifier to 35A as well... and possibly insert an inrush limiter in the ac line to save the power switch? Something like this perhaps?
https://www.digikey.com/product-detail/en/ametherm/SL32-0R536/570-1057-ND/749897
From what I gather the best way to improve bass performance is to stiffen up the power supply a bit with more uf in the filter caps. So I was thingking:
- Rewire to eliminate kit builder mistakes and noise
- Use thicker wire / Quality solder
- Use separate ground wire to each fuse block
- Make pretty wires (LOL)
- Add more uf to the PS filter caps
- Replace other old electrolytics
- Add inrush limiter to AC line
- Replace bridge rectifier with 35A if required to feed larger filter caps
After this is all done and I have a perfectly quiet amp I will proceed to install the bridge kit to run it mono for the sub.
If the above sounds better than one channel of the stereo ashley amp I am using for my subs now I will get a second DH220 and give it the same treatment and run dual mono 220's for my subs.
My friend used to power his subs with a Hafler XL-600, never forget that bass! I know I am not going to get there with this, but 400-450W of DH220 bass should be pretty sweet I am hoping!
#18 wire is plenty big enough for the high-current lines in these amplifiers as these are short runs. It is very doubtful that thicker wire will improve the bass in these amplifiers. The wire that bridges the main reservoir caps and serves for the star ground should be thicker, or even a plate as used in the P230, but that is for reasons of forming a better star ground point than improving the bass. #20 or #22 is plenty for small-signal wiring.
Cheers,
Bob