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Heathkit W-5M done! Bass Balance question

k**rkleclaire

k**rkleclaire

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Thanks for your support! I finished my first project (W-5M rebuild). replaced all caps and most resisters. Shout out to Steve-O for the support.I was shocked that it even worked on first testing, but It sounds great! I hooked it up to my vintage JBL for some blaring Mono...and after a couple of hours of grooving I checked the bass balance. Way off! couldn't get it to zero out. On the advice of a friend I checked all the voltages on all the terminal pins.( someone with more experiance would have done this first) The Au7's are reasonably in spec but the V3 Kt66 has no reading on 3&4 pins.(output Transformer) Also the #6 pins reading is negligable. The V4 KT-66 readings were close. and the V5(Rectifier) are a little low as my PT was a replacment and is running below spec 412-412 on the #2 and #8 pins. my question: is it harmful to run it like this ? It sounds good... Of course it would probably sound even better if I could overcome this. I'm relatively new at this, Advice?
Many Thanks,
Kirk
 
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I'm interested in your thread because I have two W-5Ms that I need to start soldering on and have no clue how to bias the things.
 
No they mean "bass-Bal" for bias adjustment, it's set up so that when you adjust R1 the variable pot, that you read no potential on a volt meter.

Go here, they will practically tell you how to build it.

http://www.barbwired.com/andy/w5/index.htm

I'm just now ordering the parts to make two of these. I find it costs less to build your own from the ground up, and they work and sound better :D
 
Yes, I believe your right. there are two jacks on the front, insert your Multimeter and turn the pot on top till it reads 0 volts..... so Ive been told, mine won't go to zero. Good luck on your W-5M's having two is great! if you get lost on the wiring you can always refer to the other ..thats what I did.
Kirk
 
The thing is, I have the SDS boards to replace the power supply capacitors. And well, **** I'm kinda scared to get in there and start hacking away at it. Need to find a replacement 54-32 tranny as well :|
 
The sound from these things, while they worked properly, was a-mazing. They're what got me hooked on tube amps.
 
Donkey! said:
I'm just now ordering the parts to make two of these. I find it costs less to build your own from the ground up, and they work and sound better :D
Click to expand...

Where you getting the iron? Heyboer or...? I'd like to see what you end up doing so take plenty of pics.
 
kirkleclaire said:
Thanks for your support! I finished my first project (W-5M rebuild). replaced all caps and most resisters. Shout out to Steve-O for the support.I was shocked that it even worked on first testing, but It sounds great! I hooked it up to my vintage JBL for some blaring Mono...and after a couple of hours of grooving I checked the bass balance. Way off! couldn't get it to zero out. On the advice of a friend I checked all the voltages on all the terminal pins.( someone with more experiance would have done this first) The Au7's are reasonably in spec but the V3 Kt66 has no reading on 3&4 pins.(output Transformer) Also the #6 pins reading is negligable. The V4 KT-66 readings were close. and the V5(Rectifier) are a little low as my PT was a replacment and is running below spec 412-412 on the #2 and #8 pins. my question: is it harmful to run it like this ? It sounds good... Of course it would probably sound even better if I could overcome this. I'm relatively new at this, Advice?
Many Thanks,
Kirk
Click to expand...

Kirk:

You have a serious problem if you aren,t getting any voltage at pins 3,4 & 6. BTW, pin 6 on the socket is actually just a tie point for the g2 stopper resistor so 6 & 4 should be reading the same voltage. You shouldn't be operating the amp until you've corrected this issue and can achieve proper balance. Otherwise you risk overrunning the "good" KT66 and possibly ruining it plus other damage.

First check wiring of the OPT, esp the red B+ leads. If wiring is correct, check voltages with KT66s out of the sockets but do so quickly to prevent capacitor stress because voltages will be higher than spec w/o load. If KT66 socket voltages check OK you may have a shorted KT66 (unlikely). If voltages don't check OK at this point, check continuity of the OPT primary with power off and all caps thoroughly discharged. You should get something like 300-400 ohms either side of the CT. Your symptoms point towards an open OPT primary, an unfortunately more common experience than it should be with the 16309 OPT. Hopefully not since this condition is usually fatal. What OPT do you have here?

Good luck
 
jcmjrt said:
Where you getting the iron? Heyboer or...? I'd like to see what you end up doing so take plenty of pics.
Click to expand...

Well right now I plan on buying Edcore power transformers.

And I'm either going to go with Lundahl LL1620 output tx or maybe even try the Edcore output tx

About 120 bucks for both edcores. or 64 bucks for the edcore psu tx and 110.00 for lundahl. I may go with Hammond. But I have a hard time believing they are better then lundahls.

And they cost about the same or more.

I'm using Hammond Chassis's # 1444-28

Of course, I have order double of everything.

I might design pre-amps into them seeing how I have the space. But right now plan on them just being over sized, heavily built 20 watt mono blocks.
 
Donkey! said:
Well right now I plan on buying Edcore power transformers.

And I'm either going to go with Lundahl LL1620 output tx or maybe even try the Edcore output tx
Click to expand...

Have you heard this combo before? How does it compare to refurb'd W5Ms?
 
Steve-O thanks for the helpful response. I resoldered the primary lead to no avail.I was not able to get any reading on the V3 terminals.
I was able to get a ohm reading between the OP primary and the V4 of .272. Looks as if the OP is a goner or will be soon. That said I need to replace, Can you help? Do you have thoughts on the above mentioned Lundahl's? I'm a total novice but feel I can do this. Can someone provide me with a contact and preferably a cataloge number for a replacment OP? I don't know the correct configuration. I guess I should also get a PT that is in spec also, do you have advice on that? ......$500 boat anchor???
Kirk
 
jcmjrt said:
Have you heard this combo before? How does it compare to refurb'd W5Ms?
Click to expand...

I don't know, but I can tell you Lundahl transformers are killer, something I don't hear many here talk about, but none the less. I don't think many people know of them.

I don't know how W5s sound. I've just read allot of info on them, and on paper they look great.
 
kirkleclaire said:
Steve-O thanks for the helpful response. I resoldered the primary lead to no avail.I was not able to get any reading on the V3 terminals.
I was able to get a ohm reading between the OP primary and the V4 of .272. Looks as if the OP is a goner or will be soon. That said I need to replace, Can you help? Do you have thoughts on the above mentioned Lundahl's? I'm a total novice but feel I can do this. Can someone provide me with a contact and preferably a cataloge number for a replacment OP? I don't know the correct configuration. I guess I should also get a PT that is in spec also, do you have advice on that? ......$500 boat anchor???
Kirk
Click to expand...



Before looking for OPT replacements you should verify that your OPT is truly the problem. Again with everything off and caps discharged measure resistance betw pin 3 of V3 and pin 3 of V4. It should be ~600 ohms. If you get an open circuit your OPT is probably toast. Have you verified the OPT PN#?

If you decide you need to replace the OPT you have some decisions to make. First, do you want to maintain original Heath parts? If so then you'll probably need to hit that auction place and look for a 16458. This could be costly. If you don't mind non-Heath parts you'll need an OPT of about 10K ohms P-P with g2 taps @ 40-50 % and 30-40 W. Unfortunately, Hammond doesn't really have anything like this. Closest they come is 1650F @7600 ohm P-P or 1650G @ 6600 P-P. Either can be made to work but Hammond's sec winding system doesn't allow for simple taps @4,8 & 16 ohms so you'll have to account for this.

Another alternative would be to have a custom winder such as Heyboer make up a duplicate for you. However, a one-off will be expensive so you might get involved in a group buy of something similar as is being discussed here and in the other W5 thread.

Yet another alternative would be to get your bad OPT rewound. Audio Transformers in WI can do this but they're very expensive if top-notch in their work.

I'm not very familiar with the Lundahl line so others will have to provide guidance here. Be aware that most Lundahls are very open frame and will require significant mechanical adaptation to fit the W5 Chassis if you choose this alternative.
 
Ideally, you 7.6k primaries for the w5m output box. This is what I read on their site anyways.

The 1650F from Hammond will work for either 4,8 or 16 ohms, but you have to choose one of the three, because the the secondaries not is use get connected to each other IIRC

The 1650R is a bit over kill. it's a 100 watt output box. and only 5k ct.
 
You'll need a pretty good transformer to run a Williamson design. The circuit uses a good deal of feedback, but with a decent OT, it is not a problem, but with a hammond, it might be....

I think the S-265-Q won't have any problems in this situation.

read about it here:
http://gregory.webng.com/W4/The_Williamson_Amplifier.pdf

hopefully my hosting bandwidth won't runneth over...please download it only once and save it
 
Donkey! said:
Ideally, you 7.6k primaries for the w5m output box. This is what I read on their site anyways.

The 1650F from Hammond will work for either 4,8 or 16 ohms, but you have to choose one of the three, because the the secondaries not is use get connected to each other IIRC
Click to expand...

FWIW, I meas the 16309 ~8.8K and the 16458 ~9K ohm. John Atwood meas the 309 @~12K and 458 @10K. Not sure of the source of the discrepancies but I'm confident in my meas protocol. Regardless, the 1650F should work OK. This approx load was what the Stancor UL "Williamson" amp used for 807s as did the the UL "Mullard" style Knight KB85 with EL37s so there is precedent.

Another nice OPT consideration might be the Edcor CXPP50-MS : 8.4K and 4-8 & 16 ohm taps for only $70 or thereabouts.
 
Steve O said:
I think not! That's a single ended OPT. Last I checked the W5 was PP. Also, 6.5K is kinda high for a SE 6L6 amp.
Click to expand...

Dear god, you saved me. I almost screwed up big time.

In your opinion, if one was going to use a hammond output tx for a w5m amp. Which would it be?
 
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