Haffler DH-220 upgrade path

[magconpres]

HI,

I have a Haffler DH-220 that operates find but sound a bit tired/lackluster. I got if for $150 a year ago and just through it into service. I'm thinking it's time to do some upgrades for it.

Some background on me and my skills. I understand basic electronics pretty well. I've done some HAM radio mods and do a lot of circuit building with micro-controllers, but audio is new to me, other than building a headphone app from a design on-line. Soldering skills are good. Workbench is pretty good with a temp controlled soldering iron and a Tek O-scope and a plethora of multiple meters from freebies from Harbor Freight to a Fluke benchtop.

I read Puprasmart's DH-220 Rebuild thread and found lots of interesting stuff in there.

So, my questions....
I have about $500 budgeted for the upgrade. I was leaning towards the Musical Concepts boards...either the PA6 or PA7s (hadn't decided).
For around the cost of the PA6's, I could get the Corbell designed boards mentioned in Purpasmart's thread.

Does anyone have any experience/recommendations/thoughts about one board vs the other? My thought's are that getting the Corbell based board's and buying my own components direct from Mouser is a better deal as I won't pay MC's markup on the components. But if the MC boards are better, maybe it's worth the price?

My second question is more about where to start. With the PA6's or the Corbell boards, I could likely upgrade the power supply at the same time (including new boards, considering the dual mono set up from MC). that's a bot of stretch on the budget, but not much

I think if I went with the PA7 boards, I likely couldn't even get new PS caps right now as looking at prices, a pair looks to be over $100.

Or, I could just gets some new PS caps for now and call it good till I have more cash.

Bottom line...I'm a bit stuck on where to start and what path to follow. I'm OK doing this in stages, but would like to have an end state in mind before I start so I don't buy things that I won't need/use in the end.

Thanks,
James

 

[precisionav]

HI,

I have a Haffler DH-220 that operates find but sound a bit tired/lackluster. I got if for $150 a year ago and just through it into service. I'm thinking it's time to do some upgrades for it.

Some background on me and my skills. I understand basic electronics pretty well. I've done some HAM radio mods and do a lot of circuit building with micro-controllers, but audio is new to me, other than building a headphone app from a design on-line. Soldering skills are good. Workbench is pretty good with a temp controlled soldering iron and a Tek O-scope and a plethora of multiple meters from freebies from Harbor Freight to a Fluke benchtop.

I read Puprasmart's DH-220 Rebuild thread and found lots of interesting stuff in there.

So, my questions....
I have about $500 budgeted for the upgrade. I was leaning towards the Musical Concepts boards...either the PA6 or PA7s (hadn't decided).
For around the cost of the PA6's, I could get the Corbell designed boards mentioned in Purpasmart's thread.

Does anyone have any experience/recommendations/thoughts about one board vs the other? My thought's are that getting the Corbell based board's and buying my own components direct from Mouser is a better deal as I won't pay MC's markup on the components. But if the MC boards are better, maybe it's worth the price?

My second question is more about where to start. With the PA6's or the Corbell boards, I could likely upgrade the power supply at the same time (including new boards, considering the dual mono set up from MC). that's a bot of stretch on the budget, but not much

I think if I went with the PA7 boards, I likely couldn't even get new PS caps right now as looking at prices, a pair looks to be over $100.

Or, I could just gets some new PS caps for now and call it good till I have more cash.

Bottom line...I'm a bit stuck on where to start and what path to follow. I'm OK doing this in stages, but would like to have an end state in mind before I start so I don't buy things that I won't need/use in the end.

Thanks,
James

First of all your amplifier is definitely worthy of upgrades as it is of very good design. The two options you mentioned will seriously improve on the already good sound quality. I can only speak for Musical Concepts since I upgraded my DH 500 with their boards and power supply caps some years ago. At the time it was the version 3 board. I couldn't be happier. The amp is dead quiet with no source playing and its very musical. Clean sounding with tight punchy bass and clear defined mids and highs. When upgrades are complete whichever way you go that amp will perform as good or better than many costing much, much more.

 

[Haflermichi]

Since it seems you are undecided about where to start I would ask what exactly you mean by "tired and lackluster"?
Compared to what?
Do you have experience with that amp in perfect working order? There may be nothing wrong with it and throwing new parts and pcbs
at it without a known baseline may accomplish exactly nothing but a thinner wallet.

Not that I want to discourage you from learning more and building your skills. I'm just pointing out the maxim "if it ain't broke, don't fix it".
And right now you don't know if it's "broke" or in-spec.

I would encourage you to learn how to test everything you can, starting with the PS caps.
Your bench and existing skills sound ideal for you to easily add to your knowledge and learn to check bias, dc offset, transistor function etc.
Are there faults or out of spec. components that need replacement?

Otherwise you're setting out to spend money to make changes just for the sake of change.
Now, if you want to make a project of it and learn PCB assembly and along the way a ton of practical skills that's fine.
Just make sure you understand that the amp may still sound "tired and lackluster" when you've spent all that time and money.

 

[magconpres]

Thanks for the input so far.
Haflermichi, you make a good point. I have the manual, so I should be able to check all the settings and test the ps caps easy enough. I've never tested capacitors before, but I'm sure I I can find some instructions on line. If nothing else, I can charhe them up and see if ghwy hold a charge and thwn drain them through a load and watch the drain on the scope.

As far as my comments on the amps performance, I dont think there is anything wrong as in broken with the amp. It plays fine. No woerd pops or noises. Doesnt run very hot, etc.
But tl be honest, my late 80s NAD 3220pe sounds better. Wider sound stage, more separation of instruments, etc. The Haffler sounds a bit mote comoressed to me.
I have never heard a Haffler before so I have notheing to compare this to in temrs of what it "should" sound like. But based on the reputation pf the amp, I was expecring more.

I considered just recapping it, but decided if I was going to sownd ghe time doing that, I may as well.upgrade it.

I have plenty of things to do, so while not opposed to the project am more than happy to do less to improve the sound.

Im not interested in buyong more gear. I prefer to repair and restore things over buying new. More because I think its wasteful to toss a bumch of good parts in a landfill because a $2 part hae gone bad than saving money.

Some basic tests sounds lkke a good place to start.

I'll report back.

 

[Chrispy]

Amps making differences in soundstage? Really?

 

[magconpres]

Maybe I'm usong the wrong terminology, but my nad definitley has more detail and thats just usong the power amp section (by-passing the preamp).

 

[Chrispy]

Maybe I'm usong the wrong terminology, but my nad definitley has more detail and thats just usong the power amp section (by-passing the preamp).

Level difference perhaps.

 

[phoenixdogfan]

I had a DH-200 which I built from the kit in the '70's and used it to power my Rogers LS3/5a's. I found very little to complain about. In fact I know that amp would hold up very well against most contemporary designs stock.

Here's a review with measurements. It does very well as you can see.

https://www.kenrockwell.com/audio/hafler/dh-200.htm

Personally, I'd be more interested if I still owned one of those, in just restoring it to stock condition. Maybe replace caps with comparable units, but I wouldn't redo any boards. That tiredness may very well be your caps showing their age. I'd be very wary of modding the original circuit to "improve" it. Could do a lot more harm than good.

 

[Plcamp]

HI,

I have a Haffler DH-220 that operates find but sound a bit tired/lackluster. I got if for $150 a year ago and just through it into service. I'm thinking it's time to do some upgrades for it.

Some background on me and my skills. I understand basic electronics pretty well. I've done some HAM radio mods and do a lot of circuit building with micro-controllers, but audio is new to me, other than building a headphone app from a design on-line. Soldering skills are good. Workbench is pretty good with a temp controlled soldering iron and a Tek O-scope and a plethora of multiple meters from freebies from Harbor Freight to a Fluke benchtop.

I read Puprasmart's DH-220 Rebuild thread and found lots of interesting stuff in there.

So, my questions....
I have about $500 budgeted for the upgrade. I was leaning towards the Musical Concepts boards...either the PA6 or PA7s (hadn't decided).
For around the cost of the PA6's, I could get the Corbell designed boards mentioned in Purpasmart's thread.

Does anyone have any experience/recommendations/thoughts about one board vs the other? My thought's are that getting the Corbell based board's and buying my own components direct from Mouser is a better deal as I won't pay MC's markup on the components. But if the MC boards are better, maybe it's worth the price?

My second question is more about where to start. With the PA6's or the Corbell boards, I could likely upgrade the power supply at the same time (including new boards, considering the dual mono set up from MC). that's a bot of stretch on the budget, but not much

I think if I went with the PA7 boards, I likely couldn't even get new PS caps right now as looking at prices, a pair looks to be over $100.

Or, I could just gets some new PS caps for now and call it good till I have more cash.

Bottom line...I'm a bit stuck on where to start and what path to follow. I'm OK doing this in stages, but would like to have an end state in mind before I start so I don't buy things that I won't need/use in the end.

Thanks,
James

You could consider this, it’s what Ihave done and am about to try out, having almost completed construction...https://www.ebay.ca/itm/224316431439

 

[gene_stl]

In many cases recapping is a big waste of money. So is replacing a circuit board that is working correctly with one designed by someone much less famous than David Hafler who is definitely in business to lighten peoples wallets.

Measuring the distortion of a correctly working Hafler power amp requires an elaborate and expensive set up (You could use the Quant Asylum or a good usb interface and REW ). But if the output offset is within spec, and the power output is where it belongs and the clipping is symmetric and the frequency response is within spec I wouldn't do anything to it. Also maybe check the noise output with inputs open and shorted.

 

[tomelex]

In many cases recapping is a big waste of money. So is replacing a circuit board that is working correctly with one designed by someone much less famous than David Hafler who is definitely in business to lighten peoples wallets.

Measuring the distortion of a correctly working Hafler power amp requires an elaborate and expensive set up (You could use the Quant Asylum or a good usb interface and REW ). But if the output offset is within spec, and the power output is where it belongs and the clipping is symmetric and the frequency response is within spec I wouldn't do anything to it. Also maybe check the noise output with inputs open and shorted.

Also a good idea to check mosfet bias as well, it is in the manual how to set it, make sure you take your time and do it slowly over time, as it is sensitive and needs time to settle down, if it is already really close, no need to touch it I would say. Extra heavy bias into class A does not always sound better on this amp.

 

[precisionav]

In many cases recapping is a big waste of money. So is replacing a circuit board that is working correctly with one designed by someone much less famous than David Hafler who is definitely in business to lighten peoples wallets.

Measuring the distortion of a correctly working Hafler power amp requires an elaborate and expensive set up (You could use the Quant Asylum or a good usb interface and REW ). But if the output offset is within spec, and the power output is where it belongs and the clipping is symmetric and the frequency response is within spec I wouldn't do anything to it. Also maybe check the noise output with inputs open and shorted.

There's obvious truth in what you say and your advice is reasonable. I've heard 30 year old DH200's and DH500's in stock form and they sound really good. I have great admiration and respect for Mr.. Hafler, having owned several Dyna and Hafler products. With my older Haflers I experienced board components and power supply caps of that age falling out of original spec which is normal and they can get out whack enough so that audible differences can be heard. Sure, I opted for fully loaded new boards and ps caps in both of mine from musical concepts. The price was fair and the end result brought sonic improvements that I greatly enjoy to this day. It's an option, just sayin'.

 

[gene_stl]

In my opinion musical concepts is mainly in the business of selling 1) snake oil 2) presents that people can buy for their stereo components, to make them "better".

When I see things like the following (directly quoted from their website) then I have no further interest. (bold and underscore mine):

Our PA-7 amplifier mod kit………. is now shipping. Unimaginably superior to our previous versions. We didn’t expect to make a major breakthrough but it’s here, it’s huge. We invite comparisons to anything. Discounted deals for PA-6 owners. (12-31-19, 01-20-20)

 

[tomelex]

One of the things when upgrading is figure out why you are doing it, which could just be because you have some money to spend and just want something new. However, when you bring "sound" into it, as the reason, I feel you need to be able to articulate just what "sound" you are lacking or whatever. Because if you don't, you will always be thinking the "sound" is not right forever, not that it bothers me any, but it does put you on the audio merry go around, which is OK if that is what you want to do in the hobby. Disposable income is just that, its for whatever you want to do with it, even purchasing musical concepts stuff. When they first came out, they did offer upgrades that did put better than stock components in things, so they were worthwhile initially.

 

[precisionav]

In my opinion musical concepts is mainly in the business of selling 1) snake oil 2) presents that people can buy for their stereo components, to make them "better".

When I see things like the following (directly quoted from their website) then I have no further interest. (bold and underscore mine):

Well for me it worked out pretty well when you consider its a 35 year old amplifier that I have less than 600.00 invested, including the 20 year old mods. And when we listened to it at my old job comparing new Mac's, Brystons, Classe and Krell in excess of 5k each with the Hafler sounding as good as all and better than some...I have no regrets. Have a great night.

 

[scott wurcer]

OT but I have three 220's, two should be easy to get going and one is parts only (spent a week under water). I also have two each PWM power supplies and very large capacitor banks that could be used to upgrade or build new amps.

The catch is pick-up only in Boston area, the shipping is just too much. PM if interested.

 

[Plcamp]

If you leave the 220 as designed, I would do the following minor items ...

- The power switch will be packed full of carbon dust, best replaced, but it can be taken apart, cleaned and perform like new.
- ditto on the 85 deg c thermal cutouts (one of mine had obviously overheated). Add decoupling ceramics (not in original design) across the thermal cutouts just like the one on the power switch. I replaced mine.
- The bulk caps can be replaced with new ones that will have min 10x lower esr...my old sangamo’s tested on the brink of ok, but I replaced them anyway. EPCOS makes same size replacements with great performance (but you need to cut the top terminals a bit shorter to fit.)
- Check that chassis ground connections are actually well connected. In my case the single pt chassis ground between the input jacks had paint preventing a solid chassis connection.
- the routing of the B+/- should have a dedicated wire to each fuse from the bulk cap, and not a single wire to first fuse, then a wire from that fuse to the other...this change prevents shared left right current on one wire.

and

- I am replacing convenience items like input jacks and output binding posts.

I am doing some other things as well, like adding a soft start thermistor with relay and eventually dumping output fuses in favour of FET switches ... but the above are the more important things IMO.

 

[Digital Mastering System]

First of all, it's "Cordell". Read his book. Read Self's while you're at it. I bought the PCBs off ebay and they look fine. The design is solid. Proceed with caution. The AudioExpress articles, Aug and Sept '21 I believe, have the performance and build details. This is a very good upgrade.

 

[Deleted member 26571]

So is replacing a circuit board that is working correctly with one designed by someone much less famous than David Hafler who is definitely in business to lighten peoples wallets.

Erno Borbely might take exception to this comment. Cripes.

 

[gene_stl]

And you are empowered to put words in his mouth??? Are you claiming EB designed the Musical Concepts replacement boards??
Furthermore you are a Deleted member. Go away and troll elsewhere.