Trav-Ler Portable Phonograph as a tube pre amp

clean_and_humble · Post by **clean_and_humble** » Wed Oct 15, 2014 1:23 am

Hello

Its been a minute since I posted on here. I own one of these Trav-Ler turntables and its in need of repair. The tube amp in it is simple but it has a mess of wires underneath and I am pretty sure I need new caps and it would work fine. However I would like to add a mod. I would like to add an input so I could use it as a mic pre and to run drum machines through it to warm them up. Anyone familiar with these and know the amp inside them? Is my idea possible?

This is a youtube of the model I have
http://www.youtube.com/watch?v=ZSq-Z6eKIn4

clean_and_humble · Post by **clean_and_humble** » Fri Oct 17, 2014 1:22 am

the amp looks alot like this one
http://www.ebay.com/itm/Vintage-Tube-Am ... 4d25bff0aa

floid · Post by **floid** » Fri Oct 17, 2014 7:24 am

so, a single tube design? probably a 25L6 or similar, with hot chassis. you'd have to add a preamp tube just to make it into a pretty lo-fi guitar amp.

clean_and_humble · Post by **clean_and_humble** » Mon Oct 20, 2014 12:55 am

Thanks for the reply
So in terms of reverse engineering I am trying to make this as simple as it can be. How doable would it be to put in the pre amp tube ? I know this might sound like a stupid goal but here are the attributes I find desirable about using this. One I got it for free. Two I do alot of sampling of records into an MPC 1000 and tube warmth really adds something to the sound. Also I like having the option of sampling from the on board speaker with a mic. So all that could be done without making a mod but I still have to recap and repair this unit so I thought why not mod it while I have it open. I am not expecting it as a mic pre to sound like a neve or avalon but something colorful and lo fi would not be awful. I just thought if I added a xlr in I could run a mic through and see what it sounds like also would be cool to then run the MPC through it when my beat is done to dirty it up and make it not sound so stiff the way some beats can sound. Its just a thought.

If it sounds like an awful idea I understand but what are some alternatives ?

floid · Post by **floid** » Mon Oct 20, 2014 3:57 pm

the circuit as is should take a line level signal, and you could probably find a speaker to line level converter, so that you'd have the option of mic'ing the beast up or taking the speaker out direct. you might find yourself underwhelmed. my grandfather gave me a Columbia not too dissimilar. half wave rectifier, tube heater inline with the motor, dinky little output transformer, worn out speaker. i did a recap. as a record player it was whirry and dull sounding. i built a preamp with tremelo in a separate enclosure, designed to run off my bench power supply, to feed into it to try to use it as an amp. as an amp it was whirry and dull sounding. perhaps if i'd redesigned the power supply, upgraded the transformer and speaker... and, what the hell, splurged an extra couple bucks to replace the carbon resistors, and some more for a new socket and pots... but by then i'd have built the whole thing, just to have a clone of a kay starter amp. i pulled the caps. i still use the pre as a pedal.

The Scum · Post by **The Scum** » Mon Oct 20, 2014 4:20 pm

So a couple of ghosts in the works:

Phono amplifiers usually have a really strange response curve - they attenuate the highs and boost the lows. The discs were cut with the inverse response, so for correct playback, this funny filter curve was needed. You'd have to defeat that filtering for regular response.

Tube mic preamps usually need input transformers, also.

Finally - the hot chassis thing is risky business. Isolate from the line if you're going to dig in any deeper.

If it sounds like an awful idea I understand but what are some alternatives ?

Track down the New Your Dave "One Bottle Preamp" for a simple tube preamp that much more likely to be usable. Or get the Hamptone kit for a really strong starting point.

clean_and_humble · Post by **clean_and_humble** » Tue Oct 21, 2014 1:32 am

Turns out my trav-ler turntable is not a one tube amp but it is a hot chassis I think and I understand what you are saying. I also should mention that this is not going to be my only turntable that I sample from. I have proper turntables for this. 1200's at the studio and a Lenco deck at the apt where this set up will be. So I have that for my clean proper sampling but I thought this would be good for color and variety. I also do not intend on this being my goto mic pre again just a lofi color. I guess if its totally nor doable or a bad idea to run a pic through the input where the needle hooks in and output it to a track rather than the on board speakers I can just simply restore the turntable to working and just use it as a turntable but that is not as fun.

Here are pics of my turntable showing the actual amp and diagram
does this change anything?

I am not against doing this super lofi by just connecting a mic into the plug where the needle plugs in and outputting from the mono rca . I own a Radial phono DI if that helps.

If I have to give up on this can anyone recommend a good mic pre kit for a beginner ?

clean_and_humble · Post by **clean_and_humble** » Wed Oct 29, 2014 12:55 am

After all this day dreaming about making this into a preamp/and what it does already a tube amp turntable I found this and decided instead of try and re engineer something that is A over my head in terms of DIY electronics and B is not going to sound good overall. I am just going to buy this because it does what I want it to do.....

http://www.radiomuseum.org/r/newcomb_ph ... 656_m.html

As far as this unit I thought it would be fun to just restore it and sell it but I will probably never get around to do that so maybe I should just sell it for parts....Anyhow it was fun day dreaming but I have come to my senses

for once

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Trav-Ler Portable Phonograph as a tube pre amp

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