Ampeg SVT 7 Pro Club

[Kustom_Thunder]

I gave up on mine a long time ago and went to all tube amps. My svt7 failed a number of times. I washed my hands and moved on.

 

[HaveBlue]

When I was looking for a replacement for my 7PRO I did a lot of reading up on the (perceived) reliability of bass amps. Of course, most of the information found on the internet is subjective. However, the Link Removed are widely regarded as having above-average reliability.

A lot of mid-market micro amps are built around these modules (Aguilar Tonehammer, Tecamp Puma, Eich T-series, GK combos and heads, GB Shuttle, Mesa/Boogie Subway series, Eden WTX). I'm not a product manager but what I don't understand is why a company with the heritage and the stature of Ampeg does not mate their own great tube tonestack with an externally sourced, field-proven class-D poweramp module and SMPS power supply. Think SVP-PRO-style tube preamp mated with 800 watts of Icepower modules in a <10lbs form factor of, say, a Mesa/Boogie Subway D800+. If reasonably priced, I'd buy it. I would even take the plunge and pre-order it.

 

[zigggy]

No, that's just a tolexed rack.

But if you found a 4U version of that and made a cloth cover with Ampeg classic logo and installed it in the vacant 2U under the head it'd be getting closer to what I thought. A 5U case with the cloth under would probably work best.

I don't have my 7Pro in hand yet, but the rack handles jutting out of the ears would be a dead giveaway I'm guessing.

Hi, the handles are screwed to the ears and can be removed.

 

[Sandman64]

Are the revised units still having issues? Seem this head has been out longer enough for Ampeg to have figured out all the bugs by now.

 

[Rodslinger]

All the ultra low does is cut about 10b at 500hz, it doesn't boost anything. I would say just keep the ultra low off and if you really need to, boost the lows a bit Are you EQing while you're playing alone or are you EQing while you're playing with a band? I have found, as most people do Im sure, that with the exact same EQ settings, my bass soloed sounds COMPLETELY different then how it sits in the mix. In fact, I'm not even all that pleased with how it sounds soloed, but it sits in the mix perfectly and cuts through like a knife.

It also adds 2db @40Hz when used

 

[JosephLB]

Just an update for anyone interested. Over a years worth of steady gigging and weekly practices and the new power board is holding up fine. It has been flawless since the repair.

 

[johnsonabq]

Got an issue to bounce of everyone. My 7Pro is sounding distorted. I noticed last night that even if I run straight into the amp with a known good cable, even if I turn the gain all the way down so there's no sound from the amp, The red peak led still comes on strong. I have an active bass and the -15db switch is engaged. Is this the 12ax7 tube and does it need to be replaced? I've had the amp for several years now and used it on a regular basis.

 

[beans-on-toast]

The first thing to try is a fresh battery in your bass. Eliminate that as a possible issue.

 

[johnsonabq]

The first thing to try is a fresh battery in your bass. Eliminate that as a possible issue.

As you said. That was the first thing I did.

 

[johnsonabq]

Got an issue to bounce of everyone. My 7Pro is sounding distorted. I noticed last night that even if I run straight into the amp with a known good cable, even if I turn the gain all the way down so there's no sound from the amp, The red peak led still comes on strong. I have an active bass and the -15db switch is engaged. Is this the 12ax7 tube and does it need to be replaced? I've had the amp for several years now and used it on a regular basis.

What I find strange is that the peak led lights up so much even with the gain on zero. Hmmm...

 

[beans-on-toast]

The peak light is affected by the gain relative to the compressor.

If the amp hasn't been serviced in a while, oxidation on the jacks can be an issue. There are switches (shunts) built into the jacks that the signal passes through when nothing is plugged into the jack. Oxidized shunt contacts can cause distortion. A tech would clean these with DeOxit. They would also clean the tube pins and tube socket contacts.

One way around it is to try bypassing the shunts with patch cables. It can help clean a jack by inserting and withdrawing a plug ten or so times in rapid succession into each jack. Then try inserting an instrument cable into the pre-out and power amp in jacks. If that doesn't help, insert it between the effect send and return jacks.

Next step is to replace the 12AX7 (V2). Some tips as to how to determine if a tube needs to be replaced are outlined here: How Do I Know When to Change My Tubes?

If all this fails, it would be best to have a tech check it out.

 

[johnsonabq]

The peak light is affected by the gain relative to the compressor.

If the amp hasn't been serviced in a while, oxidation on the jacks can be an issue. There are switches (shunts) built into the jacks that the signal passes through when nothing is plugged into the jack. Oxidized shunt contacts can cause distortion. A tech would clean these with DeOxit. They would also clean the tube pins and tube socket contacts.

One way around it is to try bypassing the shunts with patch cables. It can help clean a jack by inserting and withdrawing a plug ten or so times in rapid succession into each jack. Then try inserting an instrument cable into the pre-out and power amp in jacks. If that doesn't help, insert it between the effect send and return jacks.

Next step is to replace the 12AX7 (V2). Some tips as to how to determine if a tube needs to be replaced are outlined here: How Do I Know When to Change My Tubes?

If all this fails, it would be best to have a tech check it out.

I can do some cleaning with Deoxit. I've gone ahead and ordered a new tube too. If a quick tube swap can fix this it'll save a trip to the shop. Here's what I got.

Amazon.com: Tung-Sol 12AX7 Preamp Vacuum Tube, Single: Musical Instruments

 

[beans-on-toast]

I can do some cleaning with Deoxit. I've gone ahead and ordered a new tube too. If a quick tube swap can fix this it'll save a trip to the shop. Here's what I got.

Should be a good tube, I've used that make of 12AX7's. Like you said, it never hurts to do try the simple things before getting a tech involved.

 

[JimmyM]

The Tung Sol is good. I found it a tad bright, but that may sound great to you.

 

[johnsonabq]

The Tung Sol is good. I found it a tad bright, but that may sound great to you.

How many different tones are available from the different brands of tubes. What do you prefer. I didn't know it made that big a difference. This might explain the massive price difference I'm seeing. $15 to $150. I was shocked.

 

[aproud1]

How many different tones are available from the different brands of tubes. What do you prefer. I didn't know it made that big a difference. This might explain the massive price difference I'm seeing. $15 to $150. I was shocked.

Differences can be subtle especially depending on the circuit. On most bass amps I could't tell much of a difference with preamp tubes. Two it was pretty noticeable. That Tung Sol is probably pretty comparable to what ever is in there now.

Any Idea what Ampeg uses @JimmyM ? JJ?

 

[JimmyM]

How many different tones are available from the different brands of tubes. What do you prefer. I didn't know it made that big a difference. This might explain the massive price difference I'm seeing. $15 to $150. I was shocked.

You definitely don't need to spend $150. I've still got the stock JJ in mine.

Differences can be subtle especially depending on the circuit. On most bass amps I could't tell much of a difference with preamp tubes. Two it was pretty noticeable. That Tung Sol is probably pretty comparable to what ever is in there now.

Any Idea what Ampeg uses @JimmyM ? JJ?

Yep, your basic JJ ECC83 (12ax7). At least that's what mine came with. And you are correct that the difference can be subtle. The difference between the JJ and the Tung Sol in mine wasn't dramatic like it was in my SVT and V4B, but I could hear a difference in the top end. I remember a few years ago, JohnK did some tube rolling in his where he compared the stock JJ to several different NOS tubes...an Amperex Bugle Boy, a Mullard, an RCA and a Philips. Quite honestly, I was underwhelmed by the tonal differences in any of them, but there were some minor variations. They're still online if you want to have a listen:

NAD! SVT7 Pro (also comparing it to my Streamliner 900)

Post 44.

 

[johnsonabq]

You definitely don't need to spend $150. I've still got the stock JJ in mine.


Yep, your basic JJ ECC83 (12ax7). At least that's what mine came with. And you are correct that the difference can be subtle. The difference between the JJ and the Tung Sol in mine wasn't dramatic like it was in my SVT and V4B, but I could hear a difference in the top end. I remember a few years ago, JohnK did some tube rolling in his where he compared the stock JJ to several different NOS tubes...an Amperex Bugle Boy, a Mullard, an RCA and a Philips. Quite honestly, I was underwhelmed by the tonal differences in any of them, but there were some minor variations. They're still online if you want to have a listen:

NAD! SVT7 Pro (also comparing it to my Streamliner 900)

Post 44.

Thanks Jimmy!

 

[beans-on-toast]

The reasons for the price difference in tubes are many. There are newly manufactured tubes, these are less expensive, and new old stock tubes. NOS are old favorites made years ago mostly in the US, Canada, Europe, amd Japan. These are the old favorites that are long out of production and in limited supply. Because of that they cost more because of demand. The Hi-fi market tends to drive up the prices because enthusiasts will pay anything to have what they want.

So why do prices vary for currently manufactured tubes? There are differences in the cost to produce the tube, some have better materials in them, sound quality, quality control, additional screening by resellers, demand for certain products, etc.

If you don't buy a tube from a reseller that tests the tubes, matches them, and offers a warranty, you are taking a chance. Burn-in and testing are very important in weeding out early failures, noisy tubes, and ones with other issues. There are good resellers and there are bad resellers. It pays to do your homework.

Here are some good places that I have dealt with. There are others.

Invalid Link Removed

tctubes.com vintage vacuum tubes mostly NOS; very good testing - see their web site for an explanation as to what tests are performed.

www.thetubestore.com - Your online source for audio vacuum tubes.

Invalid Link Removed. These are made by JJ to Telefunken's specs.

 

[johnsonabq]

The reasons for the price difference in tubes are many. There are newly manufactured tubes, these are less expensive, and new old stock tubes. NOS are old favorites made years ago mostly in the US, Canada, Europe, amd Japan. These are the old favorites that are long out of production and in limited supply. Because of that they cost more because of demand. The Hi-fi market tends to drive up the prices because enthusiasts will pay anything to have what they want.

So why do prices vary for currently manufactured tubes? There are differences in the cost to produce the tube, some have better materials in them, sound quality, quality control, additional screening by resellers, demand for certain products, etc.

If you don't buy a tube from a reseller that tests the tubes, matches them, and offers a warranty, you are taking a chance. Good testing is very important in weeding out noisy tubes and ones with other issues. There are good resellers and there are bad resellers. It pays to do your homework.

Here are some good places that I have dealt with. There are others.

Invalid Link Removed

tctubes.com vintage vacuum tubes mostly NOS, very good testing.

www.thetubestore.com - Your online source for audio vacuum tubes.

Invalid Link Removed. These are made by JJ to Telefunken's specs.

Thanks for the good info. I did find out that the tube I bought is tested.