Thursday, April 16, 2015

Don't just power up vintage equipment after years of storage.

We all know because of power supply capacitors aging etc., to put them on variacs...but there's more. 17 years of storage did this to a friend's Marantz receiver:

17 years of storage

17 years of storage 2

It's beginning to look a lot like Christmas...time for the toothbrush and performance duster spray all came off but WOW.

Wednesday, April 15, 2015

Cheap and easy excellent tube amps


The Akai M-8 reel to reel and its re-badged versions (Roberts 770) happen to contain a completely independent pair of very high-quality tube preamps and amps which may easily be removed from the original case and with the addition of one cap value between two points, be turned into really excellent low-power single-ended tube pres/amps. The current price of these units in great condition is around $300 and you can find them for much less as well. Many of them were manufactured and I've read that many were brought to the States by soldiers purchasing them while overseas.

Mind you, we're talking 4 watts per channel at 8 ohms, but if your speakers are 90dB efficient for 1W/meter or 2.83V, and you sit near them at a desk (less than a meter from them), this is a superb project. I'm talking no hiss or hum, and the pre can be used for recording via the headphone out. There are another pair of pres in there, for phono (lacking RIAA correction) and for the tape section, which may also be brought out separately. The pre and the amp can be overdriven for special effects when recording.

We're talking single-ended design, known as being very clean and musical. Modern enthusiasts have discovered the 2A3 and rediscovered the 300B triode and there are many kit and boutique amps utilizing them from decware, tubelab, and more. 2 to 8 or so watts per channel, called "flea powered" amps, but with real detail and musicality. I built a solid-state Chipamp using tantalum resistors and it sounds fine, extremely quiet, etc. at some 70WPC. After getting these amps up and running, I've boxed and forgotten the Chipamp, only missing it for those times I really want to peel the pain off the walls.

If you use a subwoofer and highpass the audio input into these amps, 4 watts above say 150Hz or higher will be more than if loading them with full-range signal. Will be attempting this at some point.

Don't be fooled by the unit in stock condition; monitoring the Mic/Line inputs through the Speaker outputs (all 1/4" jacks) will result in quite a treble boost which is pre-emphasis for the tape section. A couple of high-voltage Mica caps totalling 375pf (used 220 + 150, parallel) across two points flatten the response (and the tape speed tone selector's 17/8 IPS setting will then provide a slight treble boost. I imagine that you could use a switch to bring in and out one of the caps which reduce the treble pre-emphasis, to act as switchable treble boost controls if you need more than provided for with the 17/8s switch.

Instructions on the net regarding disassembly come off as more complex than what I found to be the reality. Perhaps my unit was a later version because no wire clipping was required whatsoever for the basic removal and use modification. There are several multi-pin plugs which must be removed between the amps and tape section, as well as a pair of RCA jacks. One set goes to a DIN jack on the side of the cabinet; I believe this is to tap the phono output...I'm not sure as I've not concentrated upon that part so read up. I've simply disconnected it.

If you're stuck with less than 90dB efficient speakers or have a large listening space, remember that the speakers of yesteryear were designed to be loud when used in combination with such small-wattage tube amps, as are often found in vintage stereo consoles (another goldmine for tube gear, can sometimes be found for very cheap...I missed a Grundig with a reel-to-reel for $30 a few months ago).

Pioneer made a line of highly efficient speakers for hobbyists at one time, the PAX series, which save space and add to coherence by virtue of coaxial mounting. Although the frequency response of most of them will leave you needing to add a graphic EQ in order to tame them, we're talking 100+dB speakers. Put them in a 1/4 wave enclosure or full transmission line...even though they're not indestructable (20 or 30 watt limits), it'll do. Altec also made significant highly efficient coaxial designs if you're super serious about this. One company is even re-manufacturing them at the time of this writing. (Great Plains Audio.)

It bears stating that this preamp/amp combination does not impart some magical glow upon the signal. It's also not overly crisp. It's not "warm" because the treble is slightly rolled off. It just gets out of the's lacking some things which are unpleasant about less well-designed solid state gear.


Applying "audiophile" concepts to a pair of DIY speakers

When I was living with less means than today, I'd found a pair of Infinity bookshelf speakers with rotted woofer surrounds. I found a pair of Peerless Nomex 6.5" woofers at which fit the cut-out in the speaker cabinet. Being a fan of AMT and similar high frequency drivers, I found that the BG Neo 3 planar tweeter. Had to cut out an opening for them, however as they are significantly larger than the dome tweeters which came with them. Since my holes were not symmetric, I used modeling clay to seal off the inside. The cabinets are unported, are fully sealed.

This is well and good; I found some Infinity crossovers with "cups", or the fitting containing the speaker wire terminals, at a surplus store for only a few dollars. Hooked it up and it sounded fine, no distortion from a tweeter crossover too low in frequency, etc. Absolutely ludicrous to cut-and-paste a two-way crossover with drivers different than that for which it was designed, but the ears are the final master and mine said "fine".

The story does not end there...the crossover had ten cent capacitors, white sand-encased 5W resistors, cheap inductors...and I'd been reading "audiophile" sites about I unsoldered one crossover and measured the inductors and wrote up a schematic.

Over the years I've been spending a little at a time to upgrade the crossovers and I can easily tell you that there is real truth in what I've been seeing about "audiophile" technology. I've replaced the most obvious capacitor, the electrolytic one in front of the tweeter, with a good set of film capacitors, the resistors with inexpensive Mills 5W types (only a few dollars each) and one of the woofer caps with an Obbligato oil type cap. I have experienced a definite improvement in my listening. One way I've described it is that one early music CD, an Alia Vox collection, has a few pieces with vocals. Before the new resistors and caps, I used to skip a good half of the CD believing I didn't like particular songs. What was occurring is that the cheap components were resulting in a mess where the voices were too close in frequency, producing a blurry sludge. Irritating. Upon replacing the tweeter cap etc., I was suddenly interested in the entire CD...!!

Most recently I've replaced the small inductors in the tweeter circuits with $20.00 Mundorf coils. There is again a positive difference, detail revealed, depth improved, and more. But most importantly, I've taken the advice of humblehifi and bypassed the tweeter capacitor with a Vishay MKP1837 10nF (0.01uF) metalized film cap, each. Things have become even more open and detailed without anything becoming overwhelming, etc. It may be a tired metaphor but it is as if a somewhat dirty window were cleaned a bit more, revealing a bit more...

The best part? These caps cost $1.00 each. Note that some of the top audiophile caps can cost hundreds of dollars, each. You do need to have a good cap in the circuit for this bypass to really work but even a good one plus this should be a great combination. I've heard counter-melodies and details I'd never before heard in just the few CDs I've played since making this mod. I'm pulling out CDs to listen for fun, to know them better, which is the mark of any worth-while upgrade to a music system.

More: Yes, capacitors etc. take time to "burn in". I have noted a change in sonic character as this occurs as I modify these speakers. Expect it to a degree, as well.

Vishay Roederstein / ERO MKP1837 - 0,01uF / 100VDC / ± 1%


The Vishay MKP 1837 Review and Modification

Please note that excepting the Vishay bypass capacitor treatment, the differences may be described as "subtle", in that they're not huge, "everyone can hear it" differences. BUT. I'm definitely getting more out of my listening experiences as related to the Alia Vox CD. A difference compelling enough to not only keep but to pursue in other directions.

Friday, April 10, 2015

Fixing the Infinity PS210 Subwoofer

Just got a PS210 at a thrift store for cheap; plugged it in and quickly learned why...Googled its name and number plus the word "problem" and there it is; the amp is completely sealed inside a plastic chamber so air doesn't shoot out the RCA jacks, etc. This causes the amp to very quickly overheat and shut off. Right now I've got it playing happily along by removing the amp from the back panel so the tiny heatsink can breathe a minute.

When I first powered it up I experienced the dreaded Standby bug, which is it turning off the instant signal drops below a certain level. This can become oscillation. Haven't had it since removing the power supply from the cabinet. Yes, it's just sitting up against the unit, ugly as hell, so that needs to be addressed...I'm wondering about 1" nylon spacers and longer screws, so it's still mounted to the rear of the unit, but is held out enough to breathe. Ugly, but convenient.

Improvements? Mounting the amp externally with a larger heatsink. Bigger power supply capacitors (Nichicon Super Through if possible). C6 and C8...3300uF 80V. They're tall but thin so fat ones won't mount to the PCB. I like to increase both the capacitance and voltage ratings when replacing caps such as these.

That heat sink is way too small. Might need to get something better and mount the transistors to it off the PCB, requiring a bit of wiring. (This is something which apparently effects the highly-regarded Nakamichi Stasis receivers...the heat sinks don't get to breathe.)

One thing I'm noting is that the crossover frequency pot is intermittent. Its cutoff moves up and down, perhaps in league with the switch which makes it full-range. I note that pushing it a touch past its maximum setting opens it a bit more, when it's "down".

I also note that the mode switches produce a huge LF pop. Very bad. Haven't checked if that's "normal". :p

This is a nice subwoofer although I'm not yet convinced that a smaller, lighter cone isn't better for punch and kick of music versus the sustained LF rumble expected by home theatre enthusiasts.

Monday, April 6, 2015

Cluster interview (Dieter Moebius, 1997)

To: "Analogue Heaven",
From: Mike Peake,
Subject: Cluster interview (Dieter Moebius)
Date: Sun, 12 Jan 97 21:07:43 -0000

Cluster Interview

July 18, 1996. The German duo Cluster, (Dieter Moebius and Joachim
Roedelius) just did their first tour of America, despite nearly
twenty-five years of creating unique and unpretentious electronic
music. I was lucky to have had the opportunity to interview one of
the members with a friend a week after the concert at Spaceland, in
Los Angeles.

Dieter Moebius (DM), Kevin Anderson (KA), and Mike Peake (MP)

MP- Are you surprised by the response you've gotten in America on
this tour?
DM- Oh, yes, I can tell you I'm surprised, it's going so well,
and it's not always so many people, but they are all very happy and
it's really just amazing, and the fellows enjoy it a lot.
KA- Because of the response to the current tour you are doing, are
you thinking of doing any future tours, or are you just taking it one
step at a time?
DM- We are not thinking about it at all, if it happens, it would be
beautiful. Next year we have a little tour for the German Cultural
Institute, and some records to finish, so we will see.
MP- What records are you working on?
DM- We are going to make a tour CD when we finish the tour, and then
we go back and I finish a solo record that I am working on, and I
just finished a record with Neumier and a member of Die Krupps, and
have to make some edits on some things, so we are busy this year, I
MP- Have you guys always been busy with Cluster and other music?
DM- More or less; Joachim spends his time in Vienna with his wife and
children, doing his music and being a father, and I am just travelling
around, as well as making music and doing other things, some German
film music, mostly now making music again, but it was different kinds
of living in the last ten years.
KA- One of the things I'm curious about is the framework that
Cluster operates in. Mike was telling me that there is a Cluster
album about every four years or so, and then in the meantime, the two
of you each do your own thing with solo projects and collaborations
with other artists. Is that intentional, do you guys say "we'll
get back together in four years and do another album, see you 'till
DM- No, it just happens like that, it's when somebody is in a good
mood and there's some time left over and it also happens by
accident, we both have the time to meet and work on something.
MP- What countries have you had the best response from, where have
you been the most welcome with your music?
DM- It was always the United States, where we sold the most records.
MP- Really?
DM- Yes. And also the United Kingdom, and Canada, but really mostly
America. Really not so much in Germany and Europe. Italy also, but in
Italy they make lots of cassettes, and they buy not so many records.
KA- This is sort of an ongoing debate that I've been having, the
merits of vinyl verus compact discs. I was wondering what you prefer
listening to music on?
DM- Ah, I mean, from the handling it's really very good with CDs.
(laughs.) I don't like the plastic boxes, I hate them. I like the
old vinyl covers, they are bigger and it's nicer to look at, but I
hate it that all my records are broken. So, from the quality of the
sound I must say I can get along with the CD.
MP- Likewise. I don't personally care for the size (of the cover
art) with CDs. Kevin, I should mention that Moebius has done the
covers of a lot of the Cluster records and his own work; they are
always marvelous to look at and I despise the fact that the CDs are
so small. It makes me want to order a large version of the complete
work. Speaking of Cluster projects, I heard a rumor at the concert
(at Spaceland club, LA) that between Curiosum and Apropos Cluster,
there were two Cluster records released in Spain, but not
internationally. Is this true?
DM- I don't think there was anything released in Spain that was not
exported to America. I don't know now what records you mean. There
was something of (GARBLED) that came out in Spain, there was
(GARBLED)sie Hausen (??) One Hour was also released in America, and
MP- Is there any particular reason Sky Records has taken so long to
release Grosses Wasser and Curiosum on CD?
DM- I think they had some problems, first he sold all his rights for
CDs I think to a company, then he got them back. As far as I know.
KA- I'm wondering, because of what Mike was asking about the
release in Spain, the thing that came to my mind was that perhaps
that was some type of bootleg, or counterfeit record. I was wondering
if you're aware if there is sort of an underground scene, people
trading Cluster records of concerts...
DM- (Quietly) Yes, I know. There are some bootlegs I know already
that are produced in Europe and Luxembourg; we can't do anything.
I'm not anywhere (powerful), I'm not police and I'm sad because
it makes me be not more rich than I am, and I'm not anyway.
(Laughter) I'm not happy, but I can't change it.
MP- What keyboards and pieces of gear have been your favorites to
use over the years?
DM- Of course I like my very new one, the Prophecy. It's my first
real digital one, and although I tend to like to work analog, this is
a digital that's working in a way like analog, a little bit, it's
fun. I also like my JX-3P, the Roland, it's half analog; and my ARP
Odyssey and Axxe. That's all I have.
MP- You've been very prolific with those. Do you remember what
keyboard you used for the bass sound on "Oh Odessa"?
DM- Oh no! That's not really an easy question, you can kill me and
I would not know it! On which record is it?
MP- Curiosum, the first track.
DM- Curiosum. It's perhaps an ARP, but I can't say, really.
KA- Pop quiz!! (laughter). Another sort of question that's a little
bit less technical is, when you're not busy in the studio, and
writing songs for Cluster and your solo work, do you listen to music,
and if so, what are some of the bands that you are listening to now?
DM- It's a very different kind of music I listen to, I listen to
all kinds of international music, coming from every place; when I
listen to American it's mostly things like Captain Beefheart or Tom
Waits. All kinds of music, you know. What I don't listen to is
electronic music!
KA- Do you have a personal favorite Cluster album, one that you're
just more proud of than the rest?
DM- Oh, mostly the last one, One Hour I liked, and the next that's
coming, of course! (laughter) And I liked Sowiesoso, and also
Zuckerzeit, I like them. I like them all in a way.
MP- What have your favorite collaborations been?
DM- I have to say it's Mr. Beerbohm, who's my best friend. He
lives in Berlin. It just works sometimes together because it's fun.
MP- Could you tell us a little about your creative process?
DM- Oh, this is really just always improvised, and coming from one
second to the next. We always work in a multitrack studio, of course
this is more than improvising; we build up, but we begin by
improvising anyway.
MP- You're not using any computer sequencing?
DM- No no, never, never, computer sequencing, we are to stupid to
even... We're really not into computer machines, we always need
somebody else to help us record. When we make a recording just on our
DATs like One Hour, we go to a studio to get somebody to put it
MP- With the computer, the tendency is to over edit and go back and
fine tune, until the life of the performance can be extinguished.
DM- Yeah.
MP- Improvising directly to tape, that's something Cluster fans
might be tempted to try themselves.
KA- My last question is if you have any plans, because of the
enthusiasm you've been greeted with, are you even contemplating the
idea of doing a live album?
DM- We are doing a live album now, we record every show, it's going
to be a double album, and we play together with this band Bond, and
The Brain, and it's a whole big show we make, we are really five
people, they play first and then we come, and we are going to make a
big bonus track on both CDs from both Bond and The Brain, so it's
going to be a really lovely live CD of us.
KA- Will this be on Sky Records?
DM- No, it's coming out in America on Gyroscope/Cleopatra. It's
going to be "Cluster Live in America, the Erste Begegnungen (First
Encounter) tour".
MP- Will Americans be able to find any of your film music work?
DM- No, it's just in Germany.
MP- The cities you chose on the tour were probably related to record
sales over the years; I'm interested why you didn't choose to
play Detroit. I was always able to find your records there, but since
I've been in LA, it's very, very difficult (Note: this should
change with Gyroscope's recent release of the entire Cluster
catalog on CD, available through Curious Music).
DM- We would have liked to, but it didn't happen.
KA- (Laughs.) That's a very diplomatic answer.
DM- Because Diane, our fantastic tour booking agent didn't make a
booking in Detroit, because she hates the cars. (Laughter)
KA- We thank you for your time!

Contact Curious Records for the complete Cluster catalog. Many
thanks to Russ Curry of Curious Music for arranging the interview,
for making Cluster's music available in the US, and for arranging
their tour.

Curious Music
1847 Clarice Court
Coralville, Iowa



Source of Uncertainty/Stack Collision with Heap/Condemned to Freedom