Bose 901 Series II Active Equalizer #111058 Repair and Upgrade

April 16, 2014 Leave a comment

This Bose 901 Series II equalizer just came through the shop for an overhaul and upgrade. It’s in pretty good shape except for a small piece of delaminating contact paper on the side, but isn’t showing any signs of having been stored badly or abused.

The owner requested I upgrade the output capacitors to audiophile quality replacements, and add pigtail jacks to accommodate today’s thicker and more heavily shielded interconnect cables.

Inside the equalizer was all original except for the output capacitors, which had been replaced some years ago.

Component replacement and upgraded output capacitors installed next. It’s great seeing one of these cleaned up with fresh rows of components.

Finally, time to install the pigtail jacks. These are a great upgrade, and completely reversible back to the factory configuration if needed. The original ’70s RCA jacks just aren’t spaced far enough apart for most modern cables which have thicker plastic molding and thicker insulation and shielding. These OEM quality pigtails run through the center-pin holes on the RCA jacks, and provide the extra spacing to hook up your choice of cables.

Finally, time to clean the controls and move to test and pack it up! This equalizer sounded spectacular when tested out on my home system, it does the Bose 901 speaker system justice – at least as good as new, if not better. With high quality modern electrolytic filter capacitors, film output and coupling capacitors, and precision low-noise metal film resistors this equalizer will serve faithfully for many years to come.

Rain City Audio repairs Bose Active Equalizers

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1931 Westinghouse WR-8 Columaire Antique Radio Repair

April 14, 2014 Leave a comment

I recently got to work on another beautifully reconditioned Westinghouse WR-8 Columaire radio all the way from Bellingham. It was originally in for service with the SPARK Museum, but the repair technician reportedly suffered some health complications and was unable to complete the job so it came down to Seattle to finish it off. I’d previously worked on one of these back in 2013, but this one was in a bit better shape – although it took a long road to get there!

At some point in the past, the radio was badly damaged by an errant candle placed on top which must have fallen over and badly burned the top half of the radio. Afterwards, it was placed in a basement for many years and forgotten about, collecting moisture damage and dust along the way until being brought back out.

The owners spent a lot of time on the cabinet:

and reconing the speaker:

Then it was into the shop for the detailed electrical repairs!

All of the tubes in this radio tested brand new, and all the transformers and coils checked out, so it should be a pretty straightforward repair. Overwhelmingly, the resistors tested in spec also, only a few were slated for replacement. It’s been worked on before at one point, too:

An interstage transformer, normally potted in a top can, was replaced with an open-frame transformer from the late ’30s or ’40s, mounted under the chassis.

This model could be used with a phonograph or a remote control, although neither option was fitted on this model.

I began by mounting new terminal strips under the chassis, soldering them to the lugs on the old capacitor pack.

I took a slightly different approach for the other capacitor pack, using the existing phenolic board as the terminal strip after cutting off the pack capacitor.

For a size comparison, here’s a third capacitor pack containing only a single capacitor – and on top, its replacement, and a quarter for scale.

The owner requested something to make it easier to reset the clock when the time came: Molex connectors! I use 600V connectors with individual connections.

Not the prettiest, but it’ll work. The wire insulation was nicked in a few places, so I reinforced those areas with electrical tape.

Time to fire it up and test—loud and clear! I peaked up the alignment carefully and let it burn in for a while. The lead routing ultimately needed to be tweaked a little bit as there was some interference, but it was easily corrected.

After refitting both chassis and the speaker back into the cabinet, this Westinghouse was ready to go home and make warm, rich, beautiful music for many years to come.

What a beautiful piece! You’d never know how far it had to come to get to this shape. Bringing it back to life so nicely was a joint effort – without the owner’s dedication to the cosmetics of the cabinet, it would never have made it to the electrical stage.

If you need your antique radio repaired, Rain City Audio can help!




The Speaker Spotter – Speakers of Craigslist – April 11th, 2014

April 11, 2014 Leave a comment

There’s always something interesting for sale on Craigslist, especially in Seattle. Do click the titles to see the original postings with more photos and additional information if you’re interested – otherwise, enjoy the virtual window shopping! Rain City Audio is not affiliated with any of these sales; contact the respective sellers for more information. If it’s deleted, it’s probably sold already.

Today’s selection has several interesting Infinity speakers, Speakerlab 7s, and several others worth checking out!

Bose Pair of 501 Series II Direct Reflecting Speakers – $180 in Renton

BOSE pair of 501 Series II SPEAKERS

These look like they’re in pretty good shape for their age. Basically half of a Bose 601 speaker, these have a front-firing woofer and pair of angled rear-firing tweeters to produce that wide, direct/reflecting sound vintage Bose systems were known for. They’re known to be sensitive to room placement, but when set up properly are a great small floor speaker system.

Dahlquist DQ-10 – $400 in Seattle

Dahlquist DQ-10

Wide and hefty, these vintage Dahlquist speakers have a very interesting time aligned driver array and crossover network designed to maximize sonic accuracy. They’re nearly 4″ wide and weigh 62 lbs. each, delivering a flat frequency respnose 37 Hz – 27 KHz. Freshly re-foamed, too, so they should be good for a while!

Infinity Modulus Speakers – $350 in Woodinville

Infinity Modulus Speakers

These Infinity speakers are in a beautiful piano black finish and feature a 5.5″ woofer and EMIT-K tweeter in a non-resonant cabinet. The EMIT-K goes all the way to 45 khz, almost double the range of human hearing, so if your favorite music benefits from the presence of ultrasonic harmonics, these might be the speakers to get. They’d likely work well as near-field monitors, too, with the fantastically accurate planar tweeter.

Infinity Reference RS 625 Speakers – $190 in Poulsbo

Infinity Reference Standard Speakers!

These feature Polycell dome tweeters instead of EMIT planar tweeters, but would still make a fantastic surround sound system for your home theater. Quintessential 90′s look to them would match many decors, too – and a decent price!

Infinity RS 5000 – $100 in Monroe

Infinity Speakers RS 5000

From the late ’80s, these Infinity RS 5000 speakers feature a 10″ woofer and 2.5″ mi-range, both made of semi-transparent polypropylene for exceptional cone stiffness, and an EMIT-K tweeter up top. With response from 42 Hz – 45 KHz, I’d love to have a pair of these as bookshelf speakers in my office.

Legacy Audio Signature III Speakers – $1800 in Bothell

Legacy audio Signature lll

Fantastically high-end audiophile speakers, these each feature 3 x 10″ woofers, dual 7″ mid-bass drivers, a 1.25″ dome midrange, and a 4″ electrostatic ribbon driver, flat from 20 Hz – 30 kHz. With that response, and weighing in at 130 lbs. each, you wouldn’t need a subwoofer with these! Beautiful natural wood grain finish, too. I’d love to hear how these sound.

Realistic Mach One Speakers – $175 in Seattle

Mach One Radio Shack Speakers

From back when Radio Shack produced something worthwhile, these Realistic Mach One speakers are collectible and well regarded today. With a 15″ woofer, multicell exponential horn midrange and horn tweeter these speakers have a fantastic presence in the room and will reproduce 25 Hz – 20 KHz. The grilles cover the lower cabinet but leave the top multicell horn exposed, making a very interesting presence in the room. These were freshly re-foamed and re-coned, so should sound great and last for a long time.

“Set of Two Stereo Speakers” – $39 in Bellevue

set of two stereo speakers

These look like they could use some TLC, but are intriguing. The multicell horn reminds me of the Pioneer CS series from the ’60s and ’70s, and I don’t recognize anything else. They could be Pioneers which have seen better days. Might be an interesting project?

Speakerlab 7s – $499 in Tacoma

Speakerlab 7

The Speakerlab 7s were made right here in Seattle, and feature a large and highly efficient 12″ woofer, 10″ passive radiator, and use Electro-Voice drivers for the mid-range and treble horns. The vertical midrange horn will produce a fairly narrow sound field, but otherwise, these are known as thumping hard and delivering exceptional clarity. Truly a fantastic rock speaker from the classic hi-fi era.

If you’re in the market for some new speakers, please click through to the sale ads and contact the sellers! Good luck!

Other Issues of the Speaker Spotter

Important Note About “Heartbleed”

April 10, 2014 Leave a comment

This is a bit outside the normal repair shop posts you find here, but it’s important: A coding mistake that has existed for several years in one of the fundamental libraries used by about half of all servers on the Internet was recently discovered, and it’s likely being used to steal passwords and account information from all across the Internet. This is such a major issue it’s been given it’s own name, the Heartbleed bug. Companies are working frantically to secure their systems.


Mashable has some more comprehensive information, but if you use any of these services, you should change your password or your account may have been compromised:

  • Facebook
  • Instagram
  • Pinterest
  • Tumblr
  • Google (including Gmail)
  • Yahoo (including Yahoo Mail)
  • Amazon Web Services (but not Amazon Shopping)
  • GoDaddy
  • USAA
  • Intuit (TurboTax, QuickBooks, etc.)
  • DropBox
  • Minecraft
  • OKCupid
  • SoundCloud
  • Wunderlist

Be safe out there!

Bose Active Equalizer Model 800 Repair – Bose 800 Active Equalizer

April 9, 2014 1 comment

A new one for the shop, I recently worked on a Bose Active Equalizer model 800. This is very similar to the Bose 901 Series II active equalizer; the 800 series were Bose’s PA speaker series from the same model years. They featured the same cabinet design with an iconic “BOSE” grille cover, and the same 8 aligned drivers as the rear side of the 901 series. Unlike the direct/reflecting design of the 901 series, though, these are designed to face forward.

Like the Bose 901 Series II Speakers, the Bose 800 speakers need their Active Equalizer to shape the incoming signal to match the frequency response characteristics of the drivers – and same as their consumer counterparts, the capacitors fail and leak, and resistors drift out of tolerance and need to be replaced. This equalizer came to me with no output from one channel, and a strong buzz over the signal in the other channel – definitely not right.

Stage equipment frequently suffers an even harsher duty cycle than consumer gear and wears out that much more quickly. These Model 800 equalizers are rare as a result – I keep a regular eye on sales and postings, and this is only the third one I’ve ever seen.

Externally and internally, it resembles a Series II equalizer with no external controls. It has stripped out components which would otherwise have been needed for the adjustments. The curve is slightly different from the 901 series on account of the slightly different driver configuration, but realistically they could be interchanged and you’d probably never notice the difference in practice. Both have a very wide and lively sound stage.

Inside nothing looks obviously failed, but most failures of this sort happen without a lot of external evidence – especially in a low power device such as this one.

I used all Nichicon capacitors for the electrolytic replacements.

In total I replaced all the resistors and capacitors in this equalizer.

After thorough testing with a stereo analyzer and listening on my own set of Bose 901 speakers, this one was ready to go! It will serve for a long time producing the needed signal for a pair of Bose 800 or Bose 901 Series II speakers.

Bose 800 and Bose 901 Active Equalizer Repair


1946 Zenith 6-D-029 Consoltone Antique Radio Repair

April 7, 2014 1 comment

A local client just brought in a very interesting Zenith tabletop radio from just after WW2, the 1946 Zenith 6-D-029 Consoltone mantle radio. This is one of the iconic “boomerang” dials Zenith produced for a couple of years after the war. A variety of sets were made with similar styling; in this case the 6-D-029 is a 6-tube AC/DC radio with a combination of octals and loctal tubes.

This radio was repaired in the ’90s by a radio shop in Portland, OR but came to me in non-working condition. That’s not unreasonable for a radio to need another round of service after 20 years, and it looks like they did good work last time.

Checking out the tubes, other than one which was conveniently labeled (and testing confirmed) “weak”, they all had good filaments and good emissions. Something else was clearly the problem. Given the set’s owners don’t own a tube tester, the tube labeled “weak” must have been from the last time the radio was serviced; this one was the RF amplifier front-end tube.

It’s been pretty well cared for – the cabinet is in solid shape and there’s only a tiny amount of dust inside. Underneath, however…

There are several things going on here. Number one is somewhat obvious: something has released some smoke inside. In addition to that, the electrolytics used in this repair were different ages. There’s the blue CDE dual-section capacitor, and a Jamicon 33uF 450V capacitor hooked up as the second filter. Time to start pulling parts.

That Jamicon capacitor is visibly bulging from one side, and testing confirms it’s definitely dead. Of the CDE dual cap, one section was badly out of spec, and the other section tested open as well.

One of the ceramic disc capacitors blew itself apart – rather violently damaging a mylar capacitor near-by and generally making a mess of things. I replaced all of the same model of capacitor with new 630V film capacitors just to be safe.

After replacing the components it was time for the first power-up. No smoke! But, no sound either. Checking around on the voltages, something wasn’t quite right. B+ on the output tube was about 50% high, and there was no voltage on the screens of any tube.

Careful inspection and wire tracing got to the root of the problem: the wire between two tie points, supplying high voltage to the screens of the output tubes and the plate and screens of the RF and IF tubes, had broken at some point – likely from 68 years of metal fatigue. This was likely the root cause of the original failure: the ceramic disc capacitors were rated at 100V. With 4/6 tubes not conducting, the power supply was delivering over 160V when the nominal operating B+ was about 100V under load. This is well over the rating of those ceramic capacitors and could have caused the violent failure which took the radio out of service.

That’s more like it! A jumper confirms the issues has been located. The new capacitors are rated 630V, so should have no trouble with voltage spikes.

I soldered a 2″ segment of wire to make the connection permanently.

With that repair made, the radio fired up loud and clear!

Time to adjust the alignment a bit:

Then finally, back into the cabinet and ready to go home.

With all new film and electrolytic capacitors, and a replacement tube, this Zenith table radio is going to last a very long time before it needs to be serviced again and sound great the whole time.

If you need your antique radio repaired, Rain City Audio can help.

The Speaker Spotter – Speakers of Craigslist – April 4th, 2014

April 4, 2014 Leave a comment

There’s always something interesting for sale on Craigslist, especially in Seattle. Do click the titles to see the original postings with more photos and additional information if you’re interested – otherwise, enjoy the virtual window shopping! Rain City Audio is not affiliated with any of these sales; contact the respective sellers for more information. If it’s deleted, it’s probably sold already.

Today we’re featuring some speakers which are rare and nothing short of exotic – very interesting stuff!

Greybeard Audio KB22 Speakers – $800 in Renton 

Audiophile Greybeard Audio KB22 Speakers 2 Audiophile Greybeard Audio KB22 Speakers 3

Weighing in at an astonishing 115 lbs. each and with an interesting tiled case, these Greybeard Audio speakers feature a 7″ woofer and 1″ dome tweeter and handle up to 300W at 6 ohms. At that weight, these must really have next to no resonance. I’d love to hear how these sound! I know these actually sold just a little while ago, but they’re so unique they deserved including anyway.

Duntech Soverign 2001s – $6500 in Poulsbo


These astonishingly massive speakers are reportedly regarded as some of the most accurate loudspeakers in the world, with 7 drivers in a time-aligned arrangement stacked vertically and weighing in at 325 lbs. each. With such a commanding presence, these make a serious statement.

Empire Royal Grenadiers Speakers with Marble Tops – $800 in Edmonds

Empire Royal Grenadiers Speakers with marble tops Empire Royal Grenadiers Speakers with marble tops 2

These are a rare collector’s item from the 1960s and feature large cylindrical cabinets with marble tabletops. In addition to the visible drivers, there’s a 15″ downward-firing woofer in the bottom. The only trouble is, if these speakers sit without being used for many years, the woofer cone can sag out of alignment with the magnetic field and and cause poor performance. Reportedly, it can be fixed by reversing the polarity on the woofer, turning it upside down, and playing it for a while to shake the cone back into alignment although there are mixed reports of success with this approach. As long as the speakers are continually used they won’t suffer this issue but sitting for many years can cause the sag. The seller reports they don’t have a way to test them; as a part of an estate sale, I’d expect the woofer is probably suffering from sag and will need to be adjusted or replaced.

Pair of Modular Component Systems MCS 8320 Linear Phase Speakers – $65 on Vashon Island

Pair of Modular Component Systems MCS 8320 linear phase speakers

MCS was the JC Penny house brand, but in the ’70s even house brand speakers could be pretty decent. These 3-way MCS speakers feature time-corrected driver alignment.

Pair of Wharfedale PPX-1 Speakers – $60 in Northgate

Pair of Wharfedale PPX-1

These are a bit of a mystery. The seller doesn’t have much info other than they take 70W at 8 Ohms, and are 22″ x 20″ flat speakers. Are these electrostatic panels? Or a proprietary short depth speaker? Difficult to tell the date, too.

Petroff Labs Reference 3-way Speakers – $550 in Bremerton

Petroff Labs Reference 3 way speakers

Featuring 12″ woofers, 6″ midrange and a 2″ ribbon tweeter, I’m sure these interesting trapezoidal oak speakers sound as good as they look!

Polk RTIA9 Tower Speakers – $1100 in Issaquah

Polk speakers rtia9

These beastly tower speakers by Polk Audio have an interesting driver compliment – three 7″ woofers, two 5.25″ midrange drivers in their own tuned internal enclosure and a 1″ dome tweeter, these speakers are flat from 30-26,000 Hz and accept up to 500W of input power. These would be great front channels for a powerful home theatre system!

Vintage JBL C35 James B. Lansing Speakers – $1800 in Burien

Vintage JBL c35 James B. Lansing Speakers

These JBLs look to be from the late ’60s, possibly early ’70s, and seem to have a large single full-range driver installed in the cabinet. JBL’s vintage speakers are all known to be pretty fantastic and I assume these are no different.

Vintage Kenwood KL-8080X Speakers – $500 in Bremerton

Vintage Kenwood kl-8080x Speakers

These mammoth late ’70s, possibly early ’80s Kenwood speakers, feature a 5-way design in a ported enclosure with a 15″ woofer, 6″ mid, tweeter, super-tweeter, and horn with level adjustments. I’m very curious how these sound – Kenwood’s vintage products tended to be pretty well designed but I’m not familiar with these ones specifically. I do think the price is a bit high, but these have been up on Craigslist for months, the seller might be a little flexible now.

Like what you see? Check out more back issues of the Speaker Spotter.


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