Hi Mark. Yes, a renovated Hafler DH500 with modern front-end driver boards plus beefy dual mono power supply should have plenty of muscle/current to drive pretty much any speakers. I've since made similar mods to my DH500 adding the MC PS500 with 8-15000uf Mundorfs plus twin 500va toroidal transformers. Rewiring the amp helps as well replacing the old 18/20 awg wire with 12/14 awg wire thru-out the power supply and on the speaker outputs. Bill.
sounds fantastic!
Would love to hear that [fond memories of Accoustat speakers] with a "hot-rodded 500" will have great(er) headroom and sense of drive, as configured/described. The stock P/S is too anemic to deliver...
BTW, I (also) have the 8 pack of Mundorfs to use in one of my 500 chassis. They are outstanding caps!!! *which do take some time to break in.
Would love to hear that [fond memories of Accoustat speakers] with a "hot-rodded 500" will have great(er) headroom and sense of drive, as configured/described. The stock P/S is too anemic to deliver...
BTW, I (also) have the 8 pack of Mundorfs to use in one of my 500 chassis. They are outstanding caps!!! *which do take some time to break in.
Takman resister loaded boards
Hey Mark, Sorry for the delay in response, I have been building and testing amps... not near my computer.
That is a difficult question to address. A person Nth degree'ing an amp or 2, it is doable, more reasonable. Me? with over a dozen amp builds, modeling various circuit configurations... it becomes somewhat impractical. That said 1/2 of my boards are the Takman Metal Films, with a few Takman Carbon... each have virtues... Stock built/loaded MC boards sound very good.
To me, its like when I bought / owned Levinson system, I bought the *S class* or S badged gear (still own my 360S DAC, love it) In shooting Canon... I shoot mostly L-Series Lenses. If I drove a BMW, it would likely be an M Series. Not being snooty, more to serve as examples of HALO class offerings. Hmmm, to purchase and drink "Reserve"labeled - first growth wines, Cognac, etc. Where do we draw our lines???
It could be said [or argued, by the "all components measure and sound the same" crowd, which may sadly struggle to grasp component voicing / tuning prospects] The Takmans .are. among the best/most neutral resistors, especially relative to cost... I would have to agree, promote that perspective of nearly 10 years using Takmans in my system(s)
Whether a persons budget, system needs and goals (abilities to resolve) may warrant the expenditure... so many people running stock power supplies??? Takmans refinements could be lost in hierarchy of performance needs and relative virtues.
Image : example of Takman loaded PA-8 board, SOUNDS FABULOUS.
*I straightened; the FETS before final tightening a quick snap shot.
Hey Mark, Sorry for the delay in response, I have been building and testing amps... not near my computer.
That is a difficult question to address. A person Nth degree'ing an amp or 2, it is doable, more reasonable. Me? with over a dozen amp builds, modeling various circuit configurations... it becomes somewhat impractical. That said 1/2 of my boards are the Takman Metal Films, with a few Takman Carbon... each have virtues... Stock built/loaded MC boards sound very good.
To me, its like when I bought / owned Levinson system, I bought the *S class* or S badged gear (still own my 360S DAC, love it) In shooting Canon... I shoot mostly L-Series Lenses. If I drove a BMW, it would likely be an M Series. Not being snooty, more to serve as examples of HALO class offerings. Hmmm, to purchase and drink "Reserve"labeled - first growth wines, Cognac, etc. Where do we draw our lines???
It could be said [or argued, by the "all components measure and sound the same" crowd, which may sadly struggle to grasp component voicing / tuning prospects] The Takmans .are. among the best/most neutral resistors, especially relative to cost... I would have to agree, promote that perspective of nearly 10 years using Takmans in my system(s)
Whether a persons budget, system needs and goals (abilities to resolve) may warrant the expenditure... so many people running stock power supplies??? Takmans refinements could be lost in hierarchy of performance needs and relative virtues.
Image : example of Takman loaded PA-8 board, SOUNDS FABULOUS.
*I straightened; the FETS before final tightening a quick snap shot.
Attachments
Resitive loading of the output stage
~ I wanted to commit this somewhere ~ 500 thread made the most sense.
*the other* thread has become SO lopsided = should be renamed,
I digress...
The example shown is of my P230 mono, XL280 six output amp.
I think that this applies to any "Hafler" based amp, but is
more critical with the added output devices.
*My unaltered [but completely radically rebuilt] XL600 sounds raw
and unrefined by comparison to 5 other builds... *It may just get
Exicons and the O/S loading...
I have tried the SOURCE RESISTOR loading resistors along
with corresponding changes in the gate resistor, there are no Micas
used for compensation as part of the PA-7MKII/PA-8 equation.
PA-7 (hardwired p to p) behind heatsink, on board with PA-8.
I have used 4 different values (not so much my intent or desire)
but the 1% N. I. wirewounds are too expensive = price gouging.
I think (suspect) older vintage FETs would benefit from
higher values like .47 used in one amp.
I cannot hear meaningful differences in the values used, I like the
refinement so much, I want to do this to every amp I own.
The refinement(s) to my ear and in my system(s) brings the
vintage Hitachi MOSFETS, much closer to the refinement and
beauty of the Exicons, even matching their imaging holography.
I had planned to put DD Exicons in most of my gear ~ but ~
if we can get this close to a sound, "bringing the MOSFETS
closer together" I have to rethink my planning.
I am in a holding pattern... The Kitty Roe Roe likes
the Exicons, sound great and make me happy!
She plopped herself down in the midst...
~ I wanted to commit this somewhere ~ 500 thread made the most sense.
*the other* thread has become SO lopsided = should be renamed,
I digress...
The example shown is of my P230 mono, XL280 six output amp.
I think that this applies to any "Hafler" based amp, but is
more critical with the added output devices.
*My unaltered [but completely radically rebuilt] XL600 sounds raw
and unrefined by comparison to 5 other builds... *It may just get
Exicons and the O/S loading...
I have tried the SOURCE RESISTOR loading resistors along
with corresponding changes in the gate resistor, there are no Micas
used for compensation as part of the PA-7MKII/PA-8 equation.
PA-7 (hardwired p to p) behind heatsink, on board with PA-8.
I have used 4 different values (not so much my intent or desire)
but the 1% N. I. wirewounds are too expensive = price gouging.
I think (suspect) older vintage FETs would benefit from
higher values like .47 used in one amp.
I cannot hear meaningful differences in the values used, I like the
refinement so much, I want to do this to every amp I own.
The refinement(s) to my ear and in my system(s) brings the
vintage Hitachi MOSFETS, much closer to the refinement and
beauty of the Exicons, even matching their imaging holography.
I had planned to put DD Exicons in most of my gear ~ but ~
if we can get this close to a sound, "bringing the MOSFETS
closer together" I have to rethink my planning.
I am in a holding pattern... The Kitty Roe Roe likes
the Exicons, sound great and make me happy!
She plopped herself down in the midst...
Attachments
Hello all and first I must express gratitude to all the contributors to this subject! One of the best sounding amps from my past (1980's) was a DH-220 modified by a sound lab engineer (Groton Ct) that had a two level chassis with the lower being occupied by the power supply. I myself have more recently been having good success modifying adcom amps, but looking forward to hafler again! I have slowly been acquiring some of the key components to build a pair of P-230 true mono blocks. So far I have the Cordell/Savas 220C-A1 boards and P-230 OPS boards along with all the components to stuff as well as 6 matched pairs of exicons (12 total). I also have some massive heatsinks salvaged from a yamaha P-2200. My concept is to run the boards at DH-500 rail voltage and amperage. I have included the part substitutions from earlier in this thread for the higher voltage. I am now planning power supplies and want to ask if anyone has a sorted linear design (including part numbers) they would be willing to share using some of the latest ultra fast soft recovery rectifiers and a 500-600VA transformer. I was going to build Mark Johnson's quasimoto and sort it myself, but thought I would see what others have done first. Thanks
Franken' DH/MM500 modeling
Not really sure what to call this... result of brainstorming over the weekend.
I have quite a few parts [in 'anticipation' of supply chain issues] and from
"cannibalizing" a number of amps over the years to build with.
~ when building amps = I ALWAYS start with the power supply ~
with the intended [specific circuit] chosen parts and models of use.
I don't abuse my audio gear (or cars) though I do ..enjoy.. them,
drive them, never really holding back... Can never have "enough"
horsepower, current capability (torque) or dynamic headroom.
I want to push the performance properties of the 500 series closer
to that of my scratch built CLC amps, proper ~ power supplies ~
and as per, parts simply will no longer fit (completely) in box.
My goal is to build amps that are really difficult to clip (reserves)
more than "play really loud"... build the device for unfailing
demand, abilities to .really handle. the peaks...
The 500 will have a small frame below holding / enclosing
a larger portion of the P/S section + I can then squeeze (2)
1KV transformer(s) into the build. A shown on the right.
Not really sure what to call this... result of brainstorming over the weekend.
I have quite a few parts [in 'anticipation' of supply chain issues] and from
"cannibalizing" a number of amps over the years to build with.
~ when building amps = I ALWAYS start with the power supply ~
with the intended [specific circuit] chosen parts and models of use.
I don't abuse my audio gear (or cars) though I do ..enjoy.. them,
drive them, never really holding back... Can never have "enough"
horsepower, current capability (torque) or dynamic headroom.
I want to push the performance properties of the 500 series closer
to that of my scratch built CLC amps, proper ~ power supplies ~
and as per, parts simply will no longer fit (completely) in box.
My goal is to build amps that are really difficult to clip (reserves)
more than "play really loud"... build the device for unfailing
demand, abilities to .really handle. the peaks...
The 500 will have a small frame below holding / enclosing
a larger portion of the P/S section + I can then squeeze (2)
1KV transformer(s) into the build. A shown on the right.
Attachments
It's been a couple of years but I bought a replacement fan online. I don't think the original fan is made any more. I used the model number on the stock fan to find a substitute with the same specs. It mounted and connected easily and ran much better than the old fan. I'm sorry I don't think I saved any of the new model numbers or where I bought it.
Maybe start with a new fan and see if that solves the issue? Even if it is not the fan, a new fan might be a good investment in 40 year old amp.
Maybe start with a new fan and see if that solves the issue? Even if it is not the fan, a new fan might be a good investment in 40 year old amp.
I'm sorry, I don't know that fan and I'm not an expert, either. I'd check my amp and see what I installed but I sold the amp a few years ago.
Thinking back, since I could not order the model that was original, I went with-
I don't remember the search taking long and the fan I chose was a duplicate size and voltage wise of the original.
I think if you have those two areas checked off, the fan should work.
Thinking back, since I could not order the model that was original, I went with-
- Same dimensions as the original with the same mounting pattern. I wanted it to bolt on to the heat sink with the original hardware.
- Same voltage specification as the original.
I don't remember the search taking long and the fan I chose was a duplicate size and voltage wise of the original.
I think if you have those two areas checked off, the fan should work.
I just got one of these and looking to upgrade the driver board. Aside from price, is there much sonic difference between Music Concepts, Qua-co/Fantasia, and the Bob Cordell boards? I've read that the Qua-co and Bob Cordell boards are updated versions of the DH-220, so would they sound similar? Which, of all the upgrades, has the best fidelity and which has the best value? Thanks for anyone taking their time to answer.
Cordell board and parts is cheaper and sounds better. I have qua-co and an older Musical concepts board also! Cordell is the most neutral, lowest distortion. The other 2 are very much like the Hafler SE120 of the 1990s with few tweaks (newer drivers, and cascoding, current mirror) . Both have larger electrolytic caps in the feedback network , Cordell uses a servo - better bottom end.
Sounds great. I went ahead and put an order in for one. I'm liking that it has a large Class A region in the first few watts. And I'm a sucker for a better sounding bottom end as well.
Would you recommend a PS upgrade? Or just replace the two large cans? Musical concepts makes a couple boards for the DH-500. The PS-500M & PS-500V2B can be purchased as boards.
Would you recommend a PS upgrade? Or just replace the two large cans? Musical concepts makes a couple boards for the DH-500. The PS-500M & PS-500V2B can be purchased as boards.
hello and thanks for you work! can you please share how to wire the hafler dh 500 with bob cordell board