A few questions about the suitcase

[alexdecker]

Hi all

Just a few questions. First - the top case for the piano on the suitcase models, did that also come with a leg department, like the stage model?

Secondly, I have a faulty speaker unit in my suitcase. It distorts when I play the piano. Does anyone have any spare speakers lying around I could buy? I live in Denmark, Europe...

Also, would I have to tear off the grill to replace to speakers, or can I do it completely from the inside of the cabinet?

- Alex

[Student Rhodes]

There's a couple of speakers on ebay right now.  I think they're from a MkII.  I've seen many earlier alnico speakers for Mk I suitcases on ebay in the past.  You may have to be patient.  You would not have to remove the grill cloth to replace them.

[alexdecker]

Thanks for the reply

I am guessing that the mk1 featured different speaker units than the mk2, right?

What are the consensus - is it preferable to switch all the units, or keep the originals in the cabinet?

- Alex

[pianotuner steveo]

Remember, the suitcase amp is stereo. Did you troubleshoot to be sure the speaker is actually bad? I would disconnect the bad sounding speaker for a minute, then send the good side audio to the "bad" speaker. If it still sounds bad, then yes it is the speaker. If not, there is an amp problem on that side.

I personally would keep it original.

I'm not sure what you mean by leg "department", but the suitcase pianos have no legs. There are two metal braces that attach to the speaker cabinet that help stabilize the front of the piano.

[alexdecker]

Thanks. I'm going to troubleshoot a little bit more. It cand with a blown power amp, which is why I am suspecious the amp might have taken the speaker unit with it down. Just weird that it only took one unit in that side then.

Anyways, I will post an update when I know more.

Regarding the piano lid for the suitcase - do you guys know if they came with a leg department as well? Only asking because my suitcase came without a lid for the piano, and if I were to reproduce one, I was just wondering if the original also had the leg department (seeing as it was rather unnecessary I guess). 

Thanks!

- Alex

[pnoboy]

I believe Fender used different speakers at different times.  I once had a suitcase piano, a '69 model, that had the most muffled and dull sound one could imagine.  After some experimentation, I traced it to the speakers-- Fender had used the same speakers as they used in the Fender Bassman amp, and I can tell you that they were truly woofers, and couldn't produce any highs at all.  They were 4-ohm speakers, and each channel had two wired in series.  I ended up buying two 8-ohm guitar speakers, which I installed in the front baffle (the side facing the audience), and after some more experimentation, left the holes in the back baffle, where the other two speakers were, empty.  That combination produced a sound that was a tremendous improvement over the stock sound.

I have no idea how long Fender used those speakers, or when they phased them in or phased them out.  From my perspective, using them was a big mistake.  For all I know, they may have used them for a very short time.

[vanceinatlance]

I second Steveo's response. If you have the mkII Janus amp, they are notorious for bad solder connections on the harness wires that connect to the two amp boatds. I had one with that issue and it made the speaker sound very distorted.. Switching the channels, as Stevo said, can quickly help you determin if that is the issue.
I dont have a cover in front of me, but, I do believe they all had the compartment in them, unless they are a very early model. I remember carrying my snacks and some cabels n stuff in it when I was playing the clubs.

[alexdecker]

Thanks guys. I guess I will reproduce a lid with a leg compartment in it

It is the Peterson 80w design I am troubleshooting. Its a suitcase from 1970 I've located some speakers that used to be in a suitcase, that I could buy and use. But I would love if I actually didnt have to!

But alas - since the poweramp have actually been burned off, I just have a bad feeling that the speaker is done for. But then again, why wouldnt both speakers be out?

Mmh... hopefully I can get to the bottom of this. Would be too bad spending money on another speaker unit, just to find out, that it will distort as well...

- Alex

[alexdecker]

By the way - I haven't seen Raymac tines before, but as the piano is from the beginning of 1970, I wanted your opinion. I shoot a few pictures of them.

Can anyone tell me if these are Raymac?

http://imgur.com/FxM1atm,r2GoxgE

Thanks!

- Alex

[The Real MC]

They look like the Raymacs on my '67 sparkletop.  Thicker tine stock, and the tuning springs are bigger.  Two telltale marks.

[alexdecker]

I wish there was a sure sign I could tell it from. The sound of them through the Peterson amp is somewhat more bright and bell like, unlike my '72 stage that have a more bassy fuzzy sound of a sort. That of course can be a million other reasons than tine brand.

Anyone else want to chime in with their opinion on if this is Raymac or torrington?

- Alex

[pnoboy]

There are a couple of things you could do to test a speaker for gross malfunction.  Is its DC resistance what is should be?  If you carefully move the cone with your hand do you feel or hear any rubbing?  The best test, of course, is to connect the speaker to a known good amplifier.

[alexdecker]

I tried switching around all the cables, and no matter what, it is always the one unit that distorts. Furthermore, I took it out today, and when I manually push the cone, it makes this dry screeching sound, which is typical for a blown speaker (at least according to Google and Youtube). So I am close to certain that this speaker is blown. I am in the process of buying a new (old) unit. Hopefully that will solve it.

- Alex

[alexdecker]

Can anyone help me with the meaning of the numbers on my speaker? Think it has something to do with what model I should get.

The unit has a white sticker on it saying:

110296
465-013
12T6-11C

Can I find the same model, based on these numbers?

If not, does anyone know where I can get recone kits to this old speaker?

- Alex

[Student Rhodes]

465-013
12T6-11C

- Alex

465 is the Oxford OEM speaker code.  Perhaps 013 is the 13th week of 1970.  If that were the case, the date stamp on your harp is probably some time after that.

12T6 indicates it's some version of a 12 inch speaker.  I have Magnatone amps that have a similar number/letter designations.  My understanding is that it's rated similar to a Jensen C12N or P12N, Which would mean it probably has a voice coil of 1.5 inches.  My guess is it can handle 50 watts, as it's something they would have put in a Twin.

If parts are available, any reconer should be able to hook you up.  When I used to recone speakers, in a case like this, we would get parts from an aftermarket manufacturer, rather than original Oxford kits.

There's a guy selling recones for this speaker on ebay.
http://www.ebay.com/itm/VINTAGE-OXFORD-12T6-12-INCH-SPEAKER-8-OHMS-2-/151838243930

Seems a little pricey to me, but perhaps he might give you credit for your frame if you send it to him.

[alexdecker]

That was a really helpful reply, thank  you!

So am I right in believing this is not an Alnico speaker?

I am buying a set of Alnico speakers and replacing the front speakers with those, and keeping the old one to play towards the player. Hope that is a reasonable solution to this whole thing...

– Alex

[pnoboy]

That was a really helpful reply, thank  you!

So am I right in believing this is not an Alnico speaker?

I am buying a set of Alnico speakers and replacing the front speakers with those, and keeping the old one to play towards the player. Hope that is a reasonable solution to this whole thing...

– Alex

Did you check to be sure you're ordering the correct impedance speakers?  Most speakers are 8 ohm, but the suitcase piano I had long ago used either 4-ohm or 16-ohm speakers--I can't remember if each channel had two speakers in series or parallel ( it was a long time ago), but I think it was 4-ohm speakers wired in series.  Also, if the speakers are wired in series, make sure you new speakers are wired in series together. 
You can check what resistance your original speakers are by using an ohmmeter--be sure to disconnect the speakers from the amp before measuring.  Most 8-ohm speakers have a DC resistance of around 6 ohms, 4-ohm speakers, a DC resistance of around 3 ohm, and I assume 16-ohm speakers would have a DC resistance of around12 ohms (though I've never measured one).  Make this measurement on one of the good speakers, not the bad one.

[alexdecker]

Actually, gotta be honest - the suitcase came with four speakers, and I just kinda figured that it was the original speakers, which were 32ohms. But now you say so, then yes, what would have been wise of me 

By the way - I dont completely get how the resistance can be 16ohm, if you wire two 32ohm in parallel. Can anybody explain that to me in layman terms?

- Alex

[Cormac Long]

Combining resistances..
http://www.eecs.tufts.edu/~dsculley/tutorial/voltageDividers/voltdiv2.html

for series, its simple adding up the total.

For parallel, its a bit nastier
1/R total = 1/R1 + 1/R2 + ... + 1/Rn

For a simplification of this formula for combining just two resistors is..
R = (R1 x R2) / (R1 + R2)
Of in your case.. (32 x 32) / (32 + 32) = 16

[alexdecker]

Thanks for the reply. I am almost ready to begin this restoration with confidence

Another question: Since this is going to be a living room instrument, I was thinking about decoupling the front playing speakers, and only play the back speakers (the ones pointing towards the player's knees). With that in mind, a few questions popped up:

For testing, can I decouple the front speakers, without damaging the amp? If doing it properly, I would solder a 8ohm resistor in there, and wire it in serial with the speaker for a  combined resistance of 16ohm. But for testing though – can I try it without the ekstra resistor?

Secondly, everybody always talk about the suitcase amp being full bandwidth, frequency wise. But if I decouple the front speakers, and only have two 12" units speaking, will it still be full bandwidth? I wasn't sure, as it will then basically be something like a Twin instead...

What do you guys think?

– Alex

[alexdecker]

Nobody has an opinion wether or not the suitcase amp will still be full range if I decouple the two speakers facing away from the player?

- Alex

[pnoboy]

Unlike tube amplifiers, solid-state amplifiers don't need to see any specific impedance at their outputs.  I believe each channel previously had 2 speakers in series connected to it.  If you disconnect one set of 2 speakers from its respective power amp, it will be happy to have nothing plugged in to its output.  However, in so doing, you will have a weird-sounding tremolo.  You could plug one speaker into each of the 2 output amps.  This will halve the output impedance the amp sees, and for most solid-state power amps, that won't be a problem--if you don't try to push too much power out of it.  The bass response will be affected by the 2 disconnected speakers to some extent.  You could try
1) Leaving the disconnected speakers in place and disconnected.
2) Leaving the disconnected speakers in place, but with their terminals shorted together.
3) Removing the disconnected speakers, and simply leaving the holes in the speaker panel open.
4) Removing the disconnected speakers, and cutting plywood to be screwed over the holes.

Each of these options will have some effect on the sound.  Some of the differences are likely to be subtle.

[Ben Bove]

good advice.  I will also add that having the speaker cabinet close to the wall with the speakers facing the wall, will increase the sound of the bass, much like positioning a Leslie speaker right up against a wall vs. moving it away from a wall. 

You can simply A-B shotgun test which you prefer by trying with all speakers on, and what pno suggests and just disconnecting the rear speakers by the wires and leaving them in place, but still having the left and right speakers hooked up to maintain the stereo vibrato.

[alexdecker]

Okay, update on my progress. I am operating the rhodes on only two speakers now – one in each side, pointing towards my knee. It plays beautifully – when it plays. Problem is:

Sometimes, I get distortion in one side. One of the speakers will distort, either lightly or heavily. And sometimes it just plays as it should.

I am having trouble finding out what makes the speaker distort. When I plug in my headphones and listen through them, I don't get any distortion, so it should be a speaker problem.

Now, I have read some suggestions that it could be an impedance mismatch. Since I use 8ohm speakers, and only have one coupled up on each side, theoretically the power amps are needing 8 ohm more in each side. But since it is only one side that is distorting, I dont know if that is what is going on. Shouldn't both sides distort if that were the problem?

Other thing is that one power amp has the old germanium transister, and the other has new silicon transistor. A professional did the replacement, and he told me he rebiased it so everything should work. So I guess that can't be the problem? And if that were the case, the audio problems should also appear in my headphones, which they dont. Am I right?

Please let me know of any suggestions or possible solutions you could have to this problem!

– Alex

[pnoboy]

Your description is a bit confusing to me.  I believe you have one 8-ohm speaker connected to each amplifier.  Is that correct?  If that is so, then each amp is seeing an 8-ohm load, which should be fine.  If my assumption is correct, do this experiment.  Swap the speakers, so that each amp is playing through a different speaker.  So, before the swap, let's say you had the left amp connected to the left speaker, and the right amp connected to the right speaker.  After the swap, you will have the left amp connected to the right speaker, and the right amp connected to the left speaker.  Either the distorted sound will continue to come out of the same speaker or the other speaker.  If it comes out of the same speaker, you will know the problem is the speaker or its connections.  If the distorted sound comes out of the other speaker, you will know that the problem is with the amp.

[alexdecker]

You are absolutely right. I did exactly what you said, and it seems that the power amp is the problem (although I still don't know why I don't hear it in the headphones then).

Can anyone guide me to a complete list of components needed to haul over the power amp (and maybe the power supply)? I dont know much about electronics, so wanted to use this opportunity to learn a bit. If I fail, I can always purchase a brand new power amp instead of using the old ones, so thought they would be good training

– Alex

[rhodesjuzz]

The top of the suitcase has a bottom plate (wood ply) that is thinner than the stage model. It has no mounting points for the legs and if you would like to install them yourself, you have to keep in mind that the wood is too thin to carry the weight and the force that will be put to this brackets.

[alexdecker]

I dont know where you picked up that I want to put the piano on legs? On the contrary, I want to keep it as original ad possible, and overhaul and restore the original power amp and supply...

- Alex

[rhodesjuzz]

You started your question about the leg department in the top case of the suitcase piano. I must have been too enthusiastic as I made my remarks. 

Keeping your Rhodes original makes me happy. Best of luck! 

[alexdecker]

You started your question about the leg department in the top case of the suitcase piano. I must have been too enthusiastic as I made my remarks. 

Keeping your Rhodes original makes me happy. Best of luck! 

Haha, I'm sorry, you're right! I totally forgot about that, as this topic has spun out of control, and is now (to see) a general suitcase restoration three (specific to the suitcase I acquired anyways)

Thanks for the replay though!

- Alex