No Longer a Tube Amp Virgin... V-M 1428

nmwhitneyjr

nmwhitneyjr

Active Member
I took a 6 hour road trip to pick up this little Voice of Music 1428 integrated amp. I've wanted to get into tubes and the price on this was affordable. The owner had a few things replaced... one tube socket, a couple failing caps and the power cord. He also had the bias set. Seemed like this would be reasonably close to plug and play.

Once home, I dusted it, reseated the tubes, and hooked it into my Nova 8Bs. I didn't expect to be overly impressed (mainly because I rebuilt the Nova's crossovers and was under the impression that the sensitivity was somewhere in the mid 80s).

Dayumn...

The difference in sound between my Sherwood S-7100 and this little amp was night and day. I felt like that guy in the Maxell ad. I ran the amp for 5 hours straight only streaming from my iPhone via Airplay. The depth of bass, clarity of the highs, imaging were all "off-scale-high". Nothing sounded bad whether it was Chick Corea, Classical or dubstep. Even the SiriusXM talk radio stations I frequent sounded excellent.

The only two problems I noted were 1) a very low hum way down in the noise floor and 2) snare drums tended to sound a bit "splashy" (i.e. not the clear "krak" I'm used to). I think a total re-cap would likely cure those ills.

Now I'm on the hunt for the matching FM Stereo Tuner...


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Great choice! This amp is very underrated and sounds wonderful, to me it's one of the greatest bang for the buck you can find.
I would check resistors and replace all the small electrolytics and the four 0.022uf coupling caps (for these you can use some of the very good vintage russian PIO or Teflon caps).
Dandy is right, it's a very infectious and deadly disease. In 2001 when I was looking for my first tube amp (it was a Fisher 400) a guy in another forum told me "don't do it, t's an addiction and you will find yourself buying more and more of these". "Don't worry - I replied - I will not catch any disease, I just need one amp for my living room". So now I am here, with 25+ amps on my shelves... Buyer beware! :D
 
I hear what you're saying about addiction... I have nearly 50 vintage/antique electric fans around our 1600 s/f house. Tube amp cost will likely slow me down. I got this V-M for just under $200... once I've gotten the rotted floor in our bathroom replaced and spent 30 days in rehab, I plan on doing a recap, check resistors, etc.

The chassis is a bit dirty... is that safe to clean with 99.9% alcohol and a toothbrush (like cleaning off a pcb)?
 
Very nice first tube amp! I’ve missed a couple of those very “retro” cool VM units. Dont wait too long to see that the filter and coupling caps have all been done to ensure longevity of your listening pleasure
 
I've recapped three 1448's and they sound wonderful. I went the extra mile and pulled out the Tone-O-Matic circuit and replaced the PECs with quality discreet parts. Now they are something else and have tone to die for. VOM made a simple/great sounding circuit and did not need the added Tone-O-Matic thrown in there.
I have a thread of my re-cap/PEC removal on another audio forum​
I expect the 1428 is just as good sounding with a little more power to boot. You picked a winner for a simple first tube amp that sounds good. When you get around to it you can change out a few parts and make it great. Have fun!

Larry D.
 
Larry, can you post the link to your recap and PEC removal here please? I'm a new fan of PEC rebuilds, but always want to learn.
 
idadude,
Can you post a link to your re-cap/PEC removal (or send me a pm with the link)?

I'm guessing that the Tone-O-Matic circuit is why I've turned the treble down and the bass nearly all the way down?

I've ordered the Owner's and Service manuals from thevoiceofmusic.com. I'll be interested to see if it specifies the components in the PECs.
 
mmwhitneyjr - did you remove the cover of your amp or did you buy it without it?
I have both 1428 and 1448 amps and their matching tuner, great early 60s look
 
I bought it without, but the owner also had the cover. Putting that back on tonite.

I'm definitely in the market for the matching tuner. The SAC has the "mid century" bug and she's decorated our den accordingly. (Hence, this particular purchase has gotten one of the highest WAFs of any purchase during our 24 year marriage).

I've also read that these amps don't have a true mono... that it simply feeds the right channel signal to both sides. Any truth to that? If so, is there an easy mod that would sum the channels for true mono?
 
nmwhitneyjr said:
I've also read that these amps don't have a true mono... that it simply feeds the right channel signal to both sides. Any truth to that? If so, is there an easy mod that would sum the channels for true mono?
Click to expand...

Yes, it’s a very easy mod, I did it in my 1428 when I removed the tone-o-matic wafer
 
Congratulations, as my friend Raul said, these are really good amps that are often overlooked.

I was the person who drew up the schematics for the Tone-O-Matic and sent them to Larry when he rebuilt his 1448. My VMs still have the stock circuit but I hope to eventually get around to trying this mod, just out of curiosity.

In his thread on AA Larry said, "I hear way more than normal distortion when I turn either the treble or bass past 12 o'clock."

My earlier advice to Larry was that the VM tone controls require a different approach than most amps: "With other amps, it seems most people start with the tone controls at the 12:00 (noon) postition, which they assume is flat, and they will usually go up from there. With the VMs, I always start with both controls at the minimum and slowly turn them up until I like the sound."

The key is to forget about the visual position of the knobs and just use your ears. Just close your eyes and turn the knobs until you like the sound. If you use this approach you may be quite happy with the resulting sound. I have been so I've never felt the urge to mod the circuit.

Part values do drift, though, and will vary from unit to unit after so many years. So, in some cases the mod may really be necessary. For instance, if you can't get enough clean sounding Bass or Treble no matter what position the knob is in. Or, if you have distortion at all positions or too much Bass or Treble with them turned to the minimum setting. In those cases I would definitely do the mod.

Here are the links to a couple of threads over at AA that Larry started and I participated in. One of them contains the schematic of the PECs:

https://www.audioasylum.com/cgi/t.mpl?f=vintage&m=227260

https://www.audioasylum.com/cgi/t.mpl?f=vintage&m=229154

I'm not sure how good the matching tuner is. I forget if I have one buried somewhere or not. Perhaps Raul can comment on this?
 
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FlaCharlie said:
My earlier advice to Larry was that the VM tone controls require a different approach than most amps: "With other amps, it seems most people start with the tone controls at the 12:00 (noon) postition, which they assume is flat, and they will usually go up from there. With the VMs, I always start with both controls at the minimum and slowly turn them up until I like the sound."

The key is to forget about where the position of the knobs and just use your ears. If you use this approach you may be quite happy with the resulting sound. I have been so I've never felt the urge to mod the circuit.
Click to expand...

Or look at a square wave through a scope. Turn the tone pots till the wave is square.

Thanks for the PEC links!
 
Dandy said:
Or look at a square wave through a scope. Turn the tone pots till the wave is square.

Thanks for the PEC links!
Click to expand...

You're welcome. I don't have a scope and don't know how to use one. If the wave is square does that indicate a lack of distortion or that the tone is flat at that knob position?

My intent is not necessarily to get a flat response but just to get something I like. Of course, the resulting knob positions will vary depending on the speakers, room placement, music being played, etc.
 
Congrats! Amazing how good these vintage tube amps sound.. and once you go tube.. you can never go back. I wish every audio source in my house was tube amplified..
 
There is one on ebay now and they installed some kind of heat shield on it.

You may want to check the heat generated by the power tubes.

I used kitchen aluminium foil to reflect the heat in the past and it work really nicely.

My 2 cents.

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