BOSTON ACOUSTICS HD10 - Some Worthy Upgrades

[drp1003]

Hello,

Nearly 17 years ago, I bought a pair of used Boston Acoustics HD10 loudspeakers on Ebay. Luckily I had a buddy of mine pick them up locally for me, so they never had to get shipped - or more precisely never got damaged during shipping.

I've had them ever since, but haven't used them in quite a while, up until just recently anyway.

About 13 years ago, I shipped the passive radiators to a place that did speaker repair. I can't even remember the name of the company anymore. But they did a fantastic job of re-foaming the surrounds and are still in perfect condition to this day. The cost was kinda high though; I DO remember that. Almost not worth it unless you are a big big fan of these speakers, or Boston speakers in general I suppose.



Now fast-forward to today, and I just finished up some more upgrades to my HD10s:

1) I replaced those stupid worthless spring-clip speaker terminals with modern 5-way binding posts.

2) Replaced the old electrolytic capacitors on the crossover networks with new modern Dayton Audio Caps



All the parts I bought from PARTS EXPRESS. Here are the part names and numbers:


(2 EA) 260-292 Round Speaker Terminal Cup 2-15/16" Binding Post Banana Jack $5.50

(2 EA) 027-230 Dayton Audio PMPC-4.7 4.7uF 250V Precision Audio Capacitor $4.20

(2 EA) 40027-242 Dayton Audio PMPC-8.2 8.2uF 250V Precision Audio Capacitor $5.99

(2 EA) 98027-342 12uF 100V Electrolytic Non-Polarized Crossover Capacitor $0.73


The speaker terminal cups are a direct replacement. Just reuse the same screws from the old plastic terminal cups. Even the speaker wire clips fit! You do not have to modify a thing. Easy as pie! A 10 minute job. Plug and play.

The crossovers are a different matter altogether. There's some modding involved. You will need a soldering iron and related materials. Basically, you are gonna have to reuse the old speaker wires, resistors and the old coils from the original Boston crossover networks, and build a new pair of crossovers using the new capacitors. The original crossover networks were point-to-point wiring. I built the new crossovers in the same manner using a piece of 3/16 in. thick fiberboard as a base. I used zip ties instead of hot glue to secure the components to the fiberboard. This project took about three hours. I secured the new crossover networks to the speaker cabinets using screws, but perhaps gluing them in would work better.

As for the sound. Nothing to report, really. The speakers sounded great before, and they STILL sound great now after performing these mods.

Basically, all I really wanted to do with my HD10s was modernize them so that they will perform their best for the next 20 years. The 5-way binding posts helped tremendously in this regard. The capacitor/crossover network upgrade may not seem like much now, but I'd like to think that replacing old dried-up electrolytic caps with newer better-er ones is like a form of insurance/speaker protection if nothing else.

 

[bcbud3]

I use a pair of these for my main system. I refoamed both passives. Great speaker.

 

[grtpumpkin]

drp1003, Question.
Why did you use an electrolytic for the 12 uf cap? Was it the physical size? I just ordered all the caps last week from parts express. I went with all pmpc's. I'm in the process of refoaming the passive radiators and recapping. All the original yellow caps were reading a bit high according to my DATs V3 readings. One of the 12 uf caps was readin 16.3 uf & the other was reading 13.28 uf. My HD10's were manufactured in 1994.

 

[grtpumpkin]

The passives cleaned up nice but my refoam skills leave lots to be desired. When I finish these HD 10's I'm gonna have a go with some T830's I picked up for restoration. I went with Rick Cobb surrounds. I found that Simply Speakers surrounds did not fit, and would require a lot of trimming as they measure close to 2mm too large on the outside diameter.

This is very addicting.

 

[grtpumpkin]

Finished them up today. They sound great. Unfortunately I did both at the same time so I cant comment on how improved they might actually be. Next set I do I'll do one at a time and try to compare audible differences, if any. The crossovers were tedious to work with. I decided to use a larger piece of thin plywood, as the caps are so much larger, in order to keep the layout as the original. See pic.

 

[drp1003]

Finished them up today. They sound great. Unfortunately I did both at the same time so I cant comment on how improved they might actually be. Next set I do I'll do one at a time and try to compare audible differences, if any. The crossovers were tedious to work with. I decided to use a larger piece of thin plywood, as the caps are so much larger, in order to keep the layout as the original. See pic.

A while ago, I had the two midbass drivers of my HD-10s refoamed locally by a guy who does really good work. It cost a lot, but hey, go an inch, go a mile.

So that should be it: both speakers have been refoamed, both passive radiators have been refoamed, both crossover networks have been upgraded and both speaker terminals have been upgraded.

You use electrolytic caps in the woofer crossover section.

 

[sam562]

These are great speakers with surprisingly deep tight/controlled bass no doubt due to the passive radiator design.

I had kind of a weird issue when refoaming my A120's (pretty much identical to the HD10): The spiders in each speaker were causing the cone edge to be a bit recessed from the flange making it difficult to allow proper excursion when gluing. I ended up having to prop up each speaker cone above the flange using little foam circles/plugs under the voice coil and glue the new surround only to the cone.

After that glue had dried, I then finished up by gluing the surround to the flange.

I used a Springfield Speaker kit for this job because at the time (Dec 2017) LooneyTunes2001 didn't have any 10" Boston filleted surrounds on ebay.


Bass sound sample: https://streamable.com/0xuhz7

 

[drp1003]

Well, well, well. Just when I thought I was out, my HD-10s pulled me back in.... again!

As I stated in my first post above, I had the two passive radiators refoamed waaaaay back in the mid 2000s by a company whose name I can't remember.

Four years ago, I did the crossover mods and the banana plug receptacle swap.

Last spring I had the two mid-bass woofers refoamed for the first time ever by a local guy.

Well guess what? The foam surrounds on the two passive radiators died... again! But this time I did the refoam job myself. I guess you could say that I've learned a thing or two about audio since 2006, and refoaming a set of passive radiators is something I can do quite easily now.

I got the refoam kit from Simply Speakers; I bought them through AMAZON.

Now, unless a tree falls on my house and destroys these speakers, I think I can say with relative certainty that I am hopefully done with modding and fixing my wonderful set of BOSTON ACOUSTICS HD10s. But you never know!